Remove outdated logging + fix the test

[YuliiaKovalova]

This change is related to the fix https://github.com/dotnet/msbuild/pull/12416/files - ProcessTracker shouldn't be needed now.
It wasn't visible due to try/catch and while I was investigating the failure, I realized the gap.

Unhandled exception. System.InvalidOperationException: Process was not started by this object, so requested information cannot be determined. at System.Diagnostics.Process.EnsureState(State state) at System.Diagnostics.Process.get_ExitCode() at Microsoft.Build.Engine.UnitTests.BackEnd.TaskHostFactory_Tests.ProcessTracker.<>c__DisplayClass1_1.<AttachToProcess>b__0(Object sender, EventArgs e) in /home/vsts/work/1/s/src/Build.UnitTests/BackEnd/TaskHostFactory_Tests.cs:line 366 at System.Diagnostics.Process.RaiseOnExited() at System.Diagnostics.Process.CompletionCallback(Object waitHandleContext, Boolean wasSignaled) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) --- End of stack trace from previous location --- at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.CompleteWaitThreadPoolWorkItem.System.Threading.IThreadPoolWorkItem.Execute() at System.Threading.ThreadPoolWorkQueue.Dispatch() at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart() at System.Threading.Thread.StartCallback()

[Copilot]

Pull Request Overview

This PR removes outdated process tracking code and fixes a test that was experiencing unhandled exceptions. The main purpose is to clean up debugging infrastructure that is no longer needed after a previous fix and address test failures caused by improper process lifecycle management.

• Removes the entire ProcessTracker helper class and its usage from test methods
• Simplifies test execution by removing try/catch blocks that were masking the real issue
• Updates the build execution pattern to use BuildManager with proper parameters