Fix order of operations when using mkString in typeConversionInfo

[abellina]

Prior to this, the explain was broken when doing type conversions (this was found while reviewing: #2971).

      *Exec <ObjectHashAggregateExec> will run on GPU
 ; T; h; e;  ; d; a; t; a;  ; t; y; p; e;  ; o; f;  ; f; o; l; l; o; w; i; n; g;  ; e; x; p; r; e; s; s; i; o; n; s;  ; w; i; l; l;  ; b; e;  ; c; o; n; v; e; r; t; e; d;  ; i; n;  ; G; P; U;  ; r; u; n; t; i; m; e; :; 
; S; e; t; (; C; o; n; v; e; r; t; e; d;  ; D; a; t; a; T; y; p; e;  ; o; f;  ; b; u; f;  ; f; r; o; m;  ; B; i; n; a; r; y; T; y; p; e;  ; t; o;  ; A; r; r; a; y; T; y; p; e; (; I; n; t; e; g; e; r; T; y; p; e; ,; f; a; l; s; e; ); ,;  ; b; e; c; a; u; s; e;  ; C; o; n; v; e; r; t; e; d;  ; B; i; n; a; r; y; T; y; p; e;  ; t; o;  ; A; r; r; a; y; T; y; p; e; (; I; n; t; e; g; e; r; T; y; p; e; ,; f; a; l; s; e; ); ,;  ; b; e; c; a; u; s; e;  ; )

This tweaks the explain so it's in one line, and does some minor fixes. The original function duplicated the message, but I think the code I have here is safe since the typeMeta passed looks to be at the same expression level, and contains the same data as caller. It would be good to get confirmation I understood this correctly.

           *Exec <ObjectHashAggregateExec> will run on GPU. The data type of following expressions will be converted in GPU runtime: buf#10: Converted BinaryType to ArrayType(IntegerType,false)

[abellina]

build

[abellina]

@andygrove do you have any other comments for this PR?

[razajafri]

nit: string interpolator can be used here?

[razajafri]

nit: same here we can use $reasonMsg inside the string

[andygrove]

@andygrove do you have any other comments for this PR?

Sorry for the delay. LGTM.