Clean up unified BUILD selection

[mspang]

Problem

Every new variant in the unified build introduces two conditionals,
which is duplicative.

Change overview

Use a single conditional to select builds and maintain a running lists
of targets to build, and targets to test.

Testing

gn_build.sh

[github-actions]

PR #20884: Size comparison from 953abf5 to d60155a

Increases (1 build for telink)

platform	target	config	section	953abf5	d60155a	change	% change
telink	lighting-app	tlsr9518adk80d	text	583146	583150	4	0.0

Decreases (3 builds for k32w, nrfconnect, telink)

platform	target	config	section	953abf5	d60155a	change	% change
k32w	lock	k32w061+release	(read/write)	687700	687684	-16	-0.0
			.text	609892	609876	-16	-0.0
nrfconnect	all-clusters-minimal-app	nrf52840dk_nrf52840	(read/write)	1156507	1156491	-16	-0.0
			text	801780	801776	-4	-0.0
telink	light-switch-app	tlsr9518adk80d	text	566616	566614	-2	-0.0

Full report (32 builds for bl602, cc13x2_26x2, cyw30739, efr32, esp32, k32w, linux, mbed, nrfconnect, p6, telink)

platform	target	config	section	953abf5	d60155a	change	% change
bl602	lighting-app	bl602	(read/write)	1383418	1383418	0	0.0
			.bss	116978	116978	0	0.0
			.data	4480	4480	0	0.0
			.text	1053500	1053500	0	0.0
		bl602+rpc	(read/write)	1428826	1428826	0	0.0
			.bss	124418	124418	0	0.0
			.data	4600	4600	0	0.0
			.text	1085156	1085156	0	0.0
cc13x2_26x2	all-clusters-app	LP_CC2652R7	(read only)	668399	668399	0	0.0
			(read/write)	182840	182840	0	0.0
			.bss	74132	74132	0	0.0
			.data	3356	3356	0	0.0
			.rodata	88271	88271	0	0.0
			.text	579812	579812	0	0.0
	all-clusters-minimal-app	LP_CC2652R7	(read only)	634039	634039	0	0.0
			(read/write)	157700	157700	0	0.0
			.bss	73428	73428	0	0.0
			.data	3356	3356	0	0.0
			.rodata	77511	77511	0	0.0
			.text	556204	556204	0	0.0
	lock-ftd	LP_CC2652R7	(read only)	671619	671619	0	0.0
			(read/write)	169796	169796	0	0.0
			.bss	71196	71196	0	0.0
			.data	3280	3280	0	0.0
			.rodata	76411	76411	0	0.0
			.text	594728	594728	0	0.0
	lock-mtd	LP_CC2652R7	(read only)	653871	653871	0	0.0
			(read/write)	183232	183232	0	0.0
			.bss	66884	66884	0	0.0
			.data	3280	3280	0	0.0
			.rodata	101151	101151	0	0.0
			.text	552240	552240	0	0.0
	pump-app	LP_CC2652R7	(read only)	680587	680587	0	0.0
			(read/write)	161676	161676	0	0.0
			.bss	71276	71276	0	0.0
			.data	3280	3280	0	0.0
			.rodata	88771	88771	0	0.0
			.text	591332	591332	0	0.0
	pump-controller-app	LP_CC2652R7	(read only)	666387	666387	0	0.0
			(read/write)	175996	175996	0	0.0
			.bss	71396	71396	0	0.0
			.data	3276	3276	0	0.0
			.rodata	84627	84627	0	0.0
			.text	581280	581280	0	0.0
	shell	LP_CC2652R7	(read only)	660890	660890	0	0.0
			(read/write)	185852	185852	0	0.0
			.bss	76436	76436	0	0.0
			.data	3360	3360	0	0.0
			.rodata	85058	85058	0	0.0
			.text	575516	575516	0	0.0
cyw30739	light	cyw930739m2evb_01	(read/write)	581990	581990	0	0.0
			.app_xip_area	460552	460552	0	0.0
			.bss	64232	64232	0	0.0
			.data	716	716	0	0.0
			.rodata	0	0	0	0.0
			.text	112	112	0	0.0
	lock	cyw930739m2evb_01	(read/write)	587906	587906	0	0.0
			.app_xip_area	461740	461740	0	0.0
			.bss	68960	68960	0	0.0
			.data	720	720	0	0.0
			.rodata	0	0	0	0.0
			.text	112	112	0	0.0
	ota-requestor-no-progress-logging	cyw930739m2evb_01	(read/write)	585266	585266	0	0.0
			.app_xip_area	464676	464676	0	0.0
			.bss	63440	63440	0	0.0
			.data	660	660	0	0.0
			.rodata	0	0	0	0.0
			.text	112	112	0	0.0
efr32	lighting-app	BRD4161A	(read/write)	1084640	1084640	0	0.0
			.bss	133044	133044	0	0.0
			.data	2048	2048	0	0.0
			.text	949528	949528	0	0.0
		BRD4161A+rpc	(read/write)	1138932	1138932	0	0.0
			.bss	149724	149724	0	0.0
			.data	2260	2260	0	0.0
			.text	986924	986924	0	0.0
		BRD4161A+rs911x	(read/write)	950008	950008	0	0.0
			.bss	140768	140768	0	0.0
			.data	2048	2048	0	0.0
			.text	807172	807172	0	0.0
	lock-app	BRD4161A+wf200	(read/write)	1127788	1127788	0	0.0
			.bss	144136	144136	0	0.0
			.data	2056	2056	0	0.0
			.text	981576	981576	0	0.0
	window-app	BRD4161A	(read/write)	1078132	1078132	0	0.0
			.bss	134516	134516	0	0.0
			.data	2076	2076	0	0.0
			.text	941520	941520	0	0.0
esp32	all-clusters-app	c3devkit	(read only)	1021566	1021566	0	0.0
			(read/write)	1485978	1485978	0	0.0
			.dram0.bss	70080	70080	0	0.0
			.dram0.data	14600	14600	0	0.0
			.flash.rodata	215864	215864	0	0.0
			.flash.text	1021566	1021566	0	0.0
			.iram0.text	62902	62902	0	0.0
		m5stack	(read only)	1075299	1075299	0	0.0
			(read/write)	488024	488024	0	0.0
			.dram0.bss	75600	75600	0	0.0
			.dram0.data	34144	34144	0	0.0
			.flash.rodata	246284	246284	0	0.0
			.flash.text	1069915	1069915	0	0.0
			.iram0.text	123267	123267	0	0.0
k32w	light	k32w061+release	(read/write)	660748	660748	0	0.0
			.bss	69540	69540	0	0.0
			.data	1992	1992	0	0.0
			.text	583416	583416	0	0.0
	lock	k32w061+release	(read/write)	687700	687684	-16	-0.0
			.bss	70004	70004	0	0.0
			.data	2004	2004	0	0.0
			.text	609892	609876	-16	-0.0
linux	chip-tool-ipv6only	arm64	(read only)	10021084	10021084	0	0.0
			(read/write)	693617	693617	0	0.0
			.bss	42961	42961	0	0.0
			.data	3304	3304	0	0.0
			.data.rel.ro	629816	629816	0	0.0
			.dynamic	528	528	0	0.0
			.got	13616	13616	0	0.0
			.init	24	24	0	0.0
			.init_array	192	192	0	0.0
			.rodata	478236	478236	0	0.0
			.text	7965140	7965140	0	0.0
	thermostat-no-ble	arm64	(read only)	2599556	2599556	0	0.0
			(read/write)	158257	158257	0	0.0
			.bss	65249	65249	0	0.0
			.data	1704	1704	0	0.0
			.data.rel.ro	83216	83216	0	0.0
			.dynamic	528	528	0	0.0
			.got	5072	5072	0	0.0
			.init	24	24	0	0.0
			.init_array	400	400	0	0.0
			.rodata	165700	165700	0	0.0
			.text	2194112	2194112	0	0.0
mbed	lock-app	CY8CPROTO_062_4343W+release	(read only)	6224	6224	0	0.0
			(read/write)	2448952	2448952	0	0.0
			.bss	213940	213940	0	0.0
			.data	5872	5872	0	0.0
			.text	1411596	1411596	0	0.0
nrfconnect	all-clusters-app	nrf52840dk_nrf52840	(read/write)	1176443	1176443	0	0.0
			bss	142900	142900	0	0.0
			rodata	142164	142164	0	0.0
			text	812472	812472	0	0.0
	all-clusters-minimal-app	nrf52840dk_nrf52840	(read/write)	1156507	1156491	-16	-0.0
			bss	142136	142136	0	0.0
			rodata	133708	133708	0	0.0
			text	801780	801776	-4	-0.0
p6	all-clusters-app	default	(read/write)	2568432	2568432	0	0.0
			.bss	149120	149120	0	0.0
			.data	2776	2776	0	0.0
			.text	1526696	1526696	0	0.0
	all-clusters-minimal-app	default	(read/write)	2513312	2513312	0	0.0
			.bss	148400	148400	0	0.0
			.data	2776	2776	0	0.0
			.text	1471576	1471576	0	0.0
	light-app	default	(read/write)	2443296	2443296	0	0.0
			.bss	140456	140456	0	0.0
			.data	2592	2592	0	0.0
			.text	1401560	1401560	0	0.0
	lock-app	default	(read/write)	2470384	2470384	0	0.0
			.bss	140304	140304	0	0.0
			.data	2600	2600	0	0.0
			.text	1428648	1428648	0	0.0
telink	light-switch-app	tlsr9518adk80d	(read/write)	798456	798456	0	0.0
			bss	70576	70576	0	0.0
			noinit	40416	40416	0	0.0
			text	566616	566614	-2	-0.0
	lighting-app	tlsr9518adk80d	(read/write)	818496	818496	0	0.0
			bss	71420	71420	0	0.0
			noinit	40416	40416	0	0.0
			text	583146	583150	4	0.0

[woody-apple]

Fast tracking build changes