gh-79366: Fix a race condition when removing a logging handler (GH-154528)

gh-79366: Fix a race condition when removing a logging handler (GH-154528)

removeHandler() mutated the handler list in place, so if a handler was
removed while callHandlers() was iterating the same list, the following
handlers could be skipped.  Replace the list instead of mutating it.

Co-authored-by: Ben Spiller <11992588+ben-spiller@users.noreply.github.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>