Building a custom test project in-tree in dotnet/runtime triggers a MSB4120 warning.

Looks like msbuild enabled additional warning in 17.7.2 that shows up when building an in-tree project in dotnet/runtime:

`...\.nuget\packages\microsoft.dotnet.build.tasks.targetframework\8.0.0-beta.23422.1\buildMultiTargeting\Microsoft.DotNet.Build.Tasks.TargetFramework.targets(54,49): message : MSB4120: Item 'InnerBuildProjectsWithBestTargetFramework' definition within target references itself via (qualified or unqualified) metadatum 'Identity'. This can lead to unintended expansion and cross-applying of pre-existing items. More info: https://aka.ms/msbuild/metadata-self-ref ...`

More info here, https://learn.microsoft.com/en-us/visualstudio/msbuild/msbuild-batching?view=vs-2022#item-self-referencing-metadata-inside-of-a-target

Issue is located here, https://github.com/dotnet/arcade/blob/main/src/Microsoft.DotNet.Build.Tasks.TargetFramework/src/buildMultiTargeting/Microsoft.DotNet.Build.Tasks.TargetFramework.targets#L53

changing `%(Identify)` -> `%(_BestTargetFramework.Identity)` resolves the warning.

dotnet/runtime:

.net8 RC1

msbuild:

MSBuild version 17.7.2+d6990bcfa for .NET Framework
17.7.2.37605