Official build break: CoreCLR asset path missing '/' in installer subset

[dagood]

Example:

https://dev.azure.com/dnceng/internal/_build/results?buildId=493349&view=logs&j=03f0c49c-0e1a-5166-19f6-fc865fe47495&t=8ffb5fe8-216f-590f-db83-b0e95984e140&l=1033

F:\workspace\_work\1\s\.packages\microsoft.dotnet.arcade.sdk\5.0.0-beta.20071.3\tools\Sign.proj(81,5): error MSB4018: System.IO.FileNotFoundException: Could not find file 'F:\workspace\_work\1\s\artifacts\transport\coreclrSystem.Private.CoreLib.dll'.

Note transport\coreclrSystem.Private.CoreLib.dll

I think this is because of missing normalization here (#1934):

runtime/eng/liveBuilds.targets

Lines 21 to 23 in fd7a5e8

	<!-- Honor the RuntimeArtifactsPath property. -->
	<CoreCLRArtifactsPath Condition="'$(CoreCLRArtifactsPath)' == ''">$(RuntimeArtifactsPath)</CoreCLRArtifactsPath>
	<MonoArtifactsPath Condition="'$(MonoArtifactsPath)' == ''">$(RuntimeArtifactsPath)</MonoArtifactsPath>

Because that variable is used in signing here:

runtime/eng/Signing.props

Line 39 in fd7a5e8

<ItemsToSign Include="$(CoreCLRArtifactsPath)System.Private.CoreLib.dll" />

I think normalizing would fix the break.

@dotnet/runtime-infrastructure

[jaredpar]

@akoeplinger can you fix this up? Seems to be fallout from the Mono CI PR