TransactionalModePreservesAllData test is flaky

[rainersigwald]

Unrelated failure observed in #13320.

Shouldly.ShouldAssertException : buildResult
should be
True
but was
False

   at Microsoft.Build.Tasks.UnitTests.WriteLinesToFile_Tests.TransactionalModePreservesAllData() in D:\a\_work\1\s\src\Tasks.UnitTests\WriteLinesToFile_Tests.cs:line 505
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)

C:\Users\cloudtest\AppData\Local\Temp\5rqrldid.v3q\MSBuildTempn4a553ru.i1z\Temporary3ec655280eb148a09a39ab8ab5eca76a\TestProject3.csproj(7,21):  error MSB3491: Could not write lines to file "C:\Users\cloudtest\AppData\Local\Temp\5rqrldid.v3q\MSBuildTempn4a553ru.i1z\Temporary3ec655280eb148a09a39ab8ab5eca76a\output.txt". Cannot create a file when that file already exists. 
Done executing task "WriteLinesToFile" -- FAILED.
Done building target "WriteToFile" in project "TestProject3.csproj" -- FAILED.

[JanProvaznik]

might be a real bug, needs investigation what is the desirable behavior and how the test is failing