EndToEndMinimumMessageImportance test is not parallel-safe

[rainersigwald]

Just got this running locally:

 Microsoft.Build.UnitTests.XMakeAppTests.EndToEndMinimumMessageImportance(arguments: \"/v:minimal /bl\", expectedMinimumMessageImportance: Low)
Shouldly.ShouldAssertException : success\r\n    should be\r\nTrue\r\n    but was\r\nFalse
   at Microsoft.Build.UnitTests.XMakeAppTests.EndToEndMinimumMessageImportance(String arguments, MessageImportance expectedMinimumMessageImportance) in S:\work\msb2\src\MSBuild.UnitTests\XMake_Tests.cs:line 2716
   at InvokeStub_XMakeAppTests.EndToEndMinimumMessageImportance(Object, Span`1)
   at System.Reflection.MethodBaseInvoker.InvokeWithFewArgs(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
Output:
Executing [S:\work\msb2\.dotnet\dotnet.exe "S:\work\msb2\artifacts\bin\Microsoft.Build.CommandLine.UnitTests\Debug\net9.0\MSBuild.dll" /v:minimal /bl "C:\Users\raines\AppData\Local\Temp\btgp5ego.d4g\MSBuildTemp\Temporarya7239f161e43492e9ba72f00f64c9656\build.proj"]
==== OUTPUT ====
MSBuild version 17.14.0-dev-25161-01+0427e8589 for .NET
MSBUILD : Logger error MSB4104: Failed to write to log file "S:\work\msb2\artifacts\bin\Microsoft.Build.CommandLine.UnitTests\Debug\net9.0\msbuild.binlog". The process cannot access the file 'S:\work\msb2\artifacts\bin\Microsoft.Build.CommandLine.UnitTests\Debug\net9.0\msbuild.binlog' because it is being used by another process.
System.IO.IOException: The process cannot access the file 'S:\work\msb2\artifacts\bin\Microsoft.Build.CommandLine.UnitTests\Debug\net9.0\msbuild.binlog' because it is being used by another process.
   at Microsoft.Win32.SafeHandles.SafeFileHandle.CreateFile(String fullPath, FileMode mode, FileAccess access, FileShare share, FileOptions options)
   at Microsoft.Win32.SafeHandles.SafeFileHandle.Open(String fullPath, FileMode mode, FileAccess access, FileShare share, FileOptions options, Int64 preallocationSize, Nullable`1 unixCreateMode)
   at System.IO.Strategies.OSFileStreamStrategy..ctor(String path, FileMode mode, FileAccess access, FileShare share, FileOptions options, Int64 preallocationSize, Nullable`1 unixCreateMode)
   at System.IO.Strategies.FileStreamHelpers.ChooseStrategyCore(String path, FileMode mode, FileAccess access, FileShare share, FileOptions options, Int64 preallocationSize, Nullable`1 unixCreateMode)
   at System.IO.FileStream..ctor(String path, FileMode mode)
   at Microsoft.Build.Logging.BinaryLogger.Initialize(IEventSource eventSource) in S:\work\msb2\src\Build\Logging\BinaryLogger\BinaryLogger.cs:line 198
Process ID is 96764

==============

Looks like we sometimes run different commands that have -bl in them from the same working directory. We should specify a path for the binlog that is defined by the test environment so it doesn't conflict.