[CIR] Implement handling of cleanups with active flag (#187389)
This implements handling of cleanup scopes in cases where a flag is
needed to indicate whether or not the cleanup is active. This happens in
cases where a cleanup is no longer required, but it isn't at the top of
the cleanup stack so it can't be popped. A temporary variable is used to
set the cleanup to an inactive state when it is no longer needed.
Assisted-by: Cursor / claude-4.6-opus-high (implementation)
Assisted-by: Cursor / gpt-5.3-codex (tests)
