Fix missing mono jit nupkg runtime library (dotnet#47193)

Resolve race condition w/ empty Microsoft.NETCore.App.Runtime.Mono.linux-x64

With the original Subsets.props, some packaging targets are called in an AOT-only environment, and are simply missing some files (because in AOT-only, the JIT was not built). These half-empty nupkgs are uploaded during AzDO builds, after the "correct" JIT builds, and overwriting them. Make changes here to avoid replacing good packages with bad - simply do not call those targets in this situation.

eng/Subsets.props

@@ -54,7 +54,8 @@
     <DefaultHostSubsets Condition="'$(RuntimeFlavor)' == 'Mono'"></DefaultHostSubsets>
     <DefaultHostSubsets Condition="'$(RuntimeFlavor)' == 'Mono' and '$(TargetsMobile)' != 'true'">host.native</DefaultHostSubsets>
 
-    <DefaultPacksSubsets>packs.product+packs.tests</DefaultPacksSubsets>
+    <DefaultPacksSubsets>packs.product</DefaultPacksSubsets>
+    <DefaultPacksSubsets Condition="'$(BuildMonoAOTCrossCompilerOnly)' != 'true'">$(DefaultPacksSubsets)+packs.tests</DefaultPacksSubsets>
   </PropertyGroup>
 
   <PropertyGroup>
@@ -280,8 +281,8 @@
   <!-- Packs sets -->
 
   <ItemGroup Condition="$(_subset.Contains('+packs.product+'))">
-    <SharedFrameworkProjectToBuild Include="$(InstallerProjectRoot)pkg\sfx\Microsoft.NETCore.App\Microsoft.NETCore.App.Ref.sfxproj" />
-    <SharedFrameworkProjectToBuild Include="$(InstallerProjectRoot)pkg\sfx\Microsoft.NETCore.App\Microsoft.NETCore.App.Runtime.sfxproj" />
+    <SharedFrameworkProjectToBuild Condition="'$(BuildMonoAOTCrossCompilerOnly)' != 'true'" Include="$(InstallerProjectRoot)pkg\sfx\Microsoft.NETCore.App\Microsoft.NETCore.App.Ref.sfxproj" />
+    <SharedFrameworkProjectToBuild Condition="'$(BuildMonoAOTCrossCompilerOnly)' != 'true'" Include="$(InstallerProjectRoot)pkg\sfx\Microsoft.NETCore.App\Microsoft.NETCore.App.Runtime.sfxproj" />
     <SharedFrameworkProjectToBuild Condition="'$(RuntimeFlavor)' != 'Mono'" Include="$(InstallerProjectRoot)pkg\sfx\Microsoft.NETCore.App\Microsoft.NETCore.App.Host.sfxproj" />
     <SharedFrameworkProjectToBuild Condition="'$(RuntimeFlavor)' != 'Mono'" Include="$(InstallerProjectRoot)pkg\sfx\Microsoft.NETCore.App\Microsoft.NETCore.App.Crossgen2.sfxproj" />
     <SharedFrameworkProjectToBuild Condition="'$(RuntimeFlavor)' != 'Mono'" Include="$(InstallerProjectRoot)pkg\sfx\installers\dotnet-host.proj" />

eng/pipelines/runtime-official.yml

@@ -146,7 +146,7 @@ stages:
       - OSX_x64
       - Linux_x64
       jobParameters:
-        buildArgs: -s mono+libs+host+packs -c $(_BuildConfig)
+        buildArgs: -s mono+packs -c $(_BuildConfig)
                    /p:MonoCrossAOTTargetOS=Android+Browser /p:SkipMonoCrossJitConfigure=true /p:BuildMonoAOTCrossCompilerOnly=true
         nameSuffix: CrossAOT_Mono
         runtimeVariant: crossaot