Cleanup CurrentTestApplicationModuleInfo

[Youssef1313]

• Remove the unneeded isMonoMuxer local variable. The fallback already returns commandLineArguments so there is no need to special case mono per the existing logic.
• Adds a TODO for an existing suspicious code.

[Copilot]

Pull request overview

This PR cleans up CurrentTestApplicationModuleInfo in Microsoft.Testing.Platform by simplifying argument selection logic and calling out suspicious executable-detection behavior.

Changes:

• Removes the redundant isMonoMuxer local/switch arm in GetCurrentExecutableInfo.
• Adds a TODO noting suspicious logic in IsCurrentTestApplicationModuleExecutable.

[Evangelink]

Review Summary

Thanks for the cleanup, @Youssef1313! I reviewed both changes in detail.

1. Mono muxer arm removal — Correct ✅

I verified that the (_, _, true) => commandLineArguments arm was provably redundant. When mono is active, both isAppHost and isDotnetMuxer are false, so the default arm _ => commandLineArguments produces the identical result. The removal also eliminates a redundant IsCurrentTestApplicationHostMonoMuxer evaluation (which called GetProcessPath() + Path.GetFileNameWithoutExtension() a second time). Clean improvement.

2. TODO on IsCurrentTestApplicationModuleExecutable — Valid bug identification ⚠️

The processPath != ".dll" check compares a full file path to the literal ".dll", which will never match — making the property always return true. This cascades into IsAppHostOrSingleFileOrNativeAot effectively becoming !isDotnet && !isMono.

The TODO is a reasonable approach for a cleanup PR, though I'd suggest making it more descriptive (see inline comment) and/or filing an issue to track it, since the fix has behavioral implications for RetryOrchestrator and TestHostControllersTestHost.

Non-blocking suggestions

• Make TODO text more specific about why it's always true and what callers are affected
• Add a brief // includes mono muxer note to the default switch arm to preserve documentation value
• Consider adding unit tests with mocked IEnvironment/IProcessHandler for the executable info switch branches (pre-existing gap)

Overall this is a clean, low-risk change. LGTM with minor suggestions.