When building from source, don't use Microsoft.CodeAnalysis.BannedApiAnalyzers to avoid the prebuilt dependency

[dagood]

A quick fix is to move the Microsoft.CodeAnalysis.BannedApiAnalyzers line here into the earlier itemgroup:

msbuild/eng/Packages.props

Lines 46 to 53 in 15e80d5

	<ItemGroup Condition="'$(DotNetBuildFromSource)' != 'true'">
	<GlobalPackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.0" PrivateAssets="All"/>
	</ItemGroup>
	<ItemGroup>
	<GlobalPackageReference Include="Microsoft.VisualStudio.SDK.EmbedInteropTypes" Version="15.0.15" PrivateAssets="All" Condition="'$(TargetFrameworkIdentifier)' == '.NETFramework'" />
	<GlobalPackageReference Include="Microsoft.CodeAnalysis.BannedApiAnalyzers" Version="$(MicrosoftCodeAnalysisBannedApiAnalyzersVersion)" />
	</ItemGroup>

BannedApiAnalyzers has some intentional old dependencies and it's not feasible to build it during source-build. It's already been removed from source-build and we need to remove usages. dotnet/roslyn-analyzers#5619

BannedApiAnalyzers isn't one of the analyzers that ends up in the SDK product, so the only reason for source-build to build it is for code validation parity when building MSBuild's C# source code. That would help source-build developers write upstreamable code if the MSBuild C# code needs to be patched, but dev flows aren't the primary goal of source-build right now.

[rainersigwald]

Yeah, we really only need this analyzer during PR/CI builds; I'm completely fine removing it from sourcebuild. I'd happily take https://github.com/dotnet/installer/pull/12369/files#diff-46ea2c5f07c40f98cd528e95087743eaa1a8fce8fe7dadaac1bcf646acb77600