Hide Environment.CallEntryPoint in unhandled exception message

[jkotas]

The idea in #126222 was to hide CallEntryPoint helper in the unhandled exception stacktraces, but it did not actually happen.

[jkotas]

throw new Exception() before this fix prints

Unhandled exception. System.Exception: Exception of type 'System.Exception' was thrown.
   at Program.<Main>$(String[] args)
   at System.Environment.CallEntryPoint(IntPtr entryPoint, String[]* pArgument, Int32* pReturnValue, Boolean captureException, Exception* pException)

with this fix:

Unhandled exception. System.Exception: Exception of type 'System.Exception' was thrown.
   at Program.<Main>$(String[] args)

[Copilot]

Pull request overview

This PR updates CoreCLR’s exception stack trace capture logic to suppress the System.Environment.CallEntryPoint helper frame so it no longer appears in stack traces (notably for top-level/unhandled exception reporting).

Changes:

• Skip adding stack frames when the current MethodDesc is g_pEnvironmentCallEntryPointMethodDesc during StackTraceInfo::AppendElement.
• Preserve the existing filtering behavior for diagnostics-hidden frames.