ApiCompat.Task's ValidateAssemblies fails when multi-targeting with UseArtifactsOutput=true

### Describe the bug
**Microsoft.DotNet.ApiCompat.Task.ValidateAssembliesTask** fails to create a semaphore file because it expects a folder to be present which does not exist. This causes build to fail.

The task expects `obj/Project//` to exist. This is not a problem when dual-targetting on its own, but it is when `UseArtifactsOutput` is set to true.
Due to the Pivot instead of `obj/Project/Release/net8.0` folder structure we get `obj/Project/release_net8.0/`. The expected directory does not exist, and thus semaphore file creation fails. Current workaround is to add an MSBuild task to ensure the expected directory exists.

### To Reproduce

[ApiCompat.Tasks issue example.zip](https://github.com/user-attachments/files/25124329/ApiCompat.Tasks.issue.example.zip)

Attached sample project, but essentially:
1. Create `directory.build.props` in solution/project's folder and set `UseArtifactsOutput` to `true` (having it in build.props may not be necessary)
2. In the project:
2.1. Add a reference to `Microsoft.DotNet.ApiCompat.Task`
2.2. Set `` to ensure multi-targeting
2.3. Add: `true`
2.4. Set: `` to a valid value so it doesn't fail the initial check. In my case I just used the built .dll itself:
```
$(ArtifactsPath)\bin\ApiCompatReproducible\$(Configuration.ToLowerInvariant())_$(TargetFramework.ToLowerInvariant())\ApiCompatReproducible.dll
```

### Exceptions (if any)
I believe the exception originates from here:
https://github.com/dotnet/sdk/blob/v10.0.102/src/Compatibility/ApiCompat/Microsoft.DotNet.ApiCompat.Task/ValidateAssembliesTask.cs#L167
```
The "Microsoft.DotNet.ApiCompat.Task.ValidateAssembliesTask" task failed unexpectedly.
System.IO.DirectoryNotFoundException: Could not find a part of the path 'D:\vs-sandbox\ApiCompat.Tasks issue example\artifacts\obj\ApiCompatReproducible\debug\Microsoft.DotNet.ApiCompat.ValidateAssemblies.Common.semaphore'.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize)
at Microsoft.DotNet.ApiCompat.Task.ValidateAssembliesTask.ExecuteCore() in /_/src/sdk/src/Compatibility/ApiCompat/Microsoft.DotNet.ApiCompat.Task/ValidateAssembliesTask.cs:line 171
at Microsoft.NET.Build.Tasks.TaskBase.Execute() in /_/src/sdk/src/Tasks/Common/TaskBase.cs:line 45
at Microsoft.DotNet.ApiCompat.Task.ValidateAssembliesTask.Execute() in /_/src/sdk/src/Compatibility/ApiCompat/Microsoft.DotNet.ApiCompat.Task/ValidateAssembliesTask.cs:line 125
at Microsoft.Build.BackEnd.TaskExecutionHost.Execute()
at Microsoft.Build.BackEnd.TaskBuilder.d__26.MoveNext()
```

### Further technical details
This has been 'fixed' (with a workaround) for Validate**Packages**, but not Validate**Assemblies** here: https://github.com/dotnet/sdk/pull/31906#pullrequestreview-1394767907
details of dotnet --info

Host:
Version: 10.0.2
Architecture: x64
Commit: 4452502459

.NET SDKs installed:
8.0.417 [C:\Program Files\dotnet\sdk]
9.0.308 [C:\Program Files\dotnet\sdk]
9.0.309 [C:\Program Files\dotnet\sdk]
10.0.102 [C:\Program Files\dotnet\sdk]