fixup! Fix load order of ProjectStaging and restrict package version validation to only official builds

Author: RussKie

Diff for: eng/MSBuild/ProjectStaging.props

@@ -14,15 +14,14 @@
         In 8.0, we shipped Microsoft.AspNetCore.Testing package as stable even when it was in the dev stage, so we
         keep it as stable for compatiblity.
       -->
-    <DotNetFinalVersionKind Condition=" '$(configureDotNetFinalVersionKind)' == 'true' And '$(DotNetFinalVersionKind)' == '' And '$(_IsStable)' == 'true' ">release</DotNetFinalVersionKind>
+    <DotNetFinalVersionKind Condition=" '$(StabilizePackageVersion)' == 'true' And '$(DotNetFinalVersionKind)' == '' And '$(_IsStable)' == 'true' ">release</DotNetFinalVersionKind>
 
     <!-- Preview packages: do not use stable branding and do not warn about lack of [Experimental] -->
     <NoWarn Condition="'$(Stage)' == 'dev' or '$(Stage)' == 'preview'">$(NoWarn);LA0003</NoWarn>
     <!--
         Makes it such that the package version won't be stabilized even when the rest of the repo is going stable.
         https://github.com/dotnet/arcade/blob/main/Documentation/CorePackages/Versioning.md#package-version
       -->
-    <SuppressFinalPackageVersion />
     <SuppressFinalPackageVersion Condition=" '$(_IsStable)' != 'true' ">true</SuppressFinalPackageVersion>
   </PropertyGroup>
 </Project>

Diff for: eng/Versions.props

@@ -9,9 +9,9 @@
     <ApiCompatBaselineVersion>9.3.0</ApiCompatBaselineVersion>
     <AssemblyVersion>$(MajorVersion).$(MinorVersion).0.0</AssemblyVersion>
     <!--
-        When DotNetFinalVersionKind is set to 'release', this branch will produce stable outputs for 'Shipping' packages
+        When StabilizePackageVersion is set to 'true', this branch will produce stable outputs for 'Shipping' packages
     -->
-    <DotNetFinalVersionKind />
+    <StabilizePackageVersion Condition="'$(StabilizePackageVersion)' == ''">false</StabilizePackageVersion>
     <!-- Enabling this rule will cause build failures on undocumented public APIs. -->
     <SkipArcadeNoWarnCS1591>true</SkipArcadeNoWarnCS1591>
   </PropertyGroup>