Close remaining unit test gaps and tidy test noise #144

Follow-up to #137 after #138-#141 and #143 were merged. CI now reports coverage: 92% on master (Tests 3.14 job on #143).

Remaining meaningful gaps:

• util.RequestUtil.get_request_from_call_stack: the req local, the any-local fallback and the calling-frame search are untested.
• JSONLogFormatter.get_exc_fields with cached exc_text and no exc_info.
• config_root_logger() success path (switching root handlers to JSON).
• FastAPI: non-FastAPI app rejection, get_protocol fallback to the empty value, header lookup failure.
• Quart: get_remote_user, header lookup, correlation id outside a request, request field getters.

Intentionally not covered: the ImportError fallbacks for frameworks that are not installed, the abstract-method bodies in framework_base.py, and the Connexion 2 / Starlette-request branches that need a different Connexion major version.

Also noted while running the suite locally: Sanic's test client logs Task was destroyed but it is pending at teardown of tests/test_sanic.py. It does not fail any test; worth checking if it is a teardown issue in the tests or in Sanic's test client.