Replace bare except with except Exception in task-sdk supervisor

[bramhanandlingala]

Description

Issue #69441 flags exception handlers that catch overly broad types,
which can hide real errors or interfere with signal handling. I looked
for bare except: clauses specifically, since those catch everything
including KeyboardInterrupt/SystemExit. There were two left in the
repo outside of tests/docs.

1. Task-SDK supervisor — the bare except around coordinator init
always re-raised afterward, so signals weren't actually swallowed, just
logged with a misleading traceback before exiting. Narrowed to
except Exception: so real errors are still logged the same way, but
Ctrl+C/shutdown no longer produce that spurious log line.

2. Pytest plugin — a bare except: raise that did nothing (pure
re-raise, no logging). Removed it; the finally below already handles
cleanup.

Didn't touch the other except Exception: blocks in core — those don't
have this bare-except issue, and a full rewrite is a separate effort.

related: #69441

[Vamsi-klu]

Verified both hunks against head. In supervisor.py the handler is log.exception(...) then raise, and for_queue only raises Exception subclasses (InvalidCoordinatorError/ValueError, plus any failure from the dynamically import_string-loaded coordinator class), so narrowing bare except: to except Exception: is behavior-preserving for every real error. The only runtime effect is that KeyboardInterrupt/SystemExit no longer get an extra traceback logged on their way out -- note they were already re-raised by the raise under the old bare except, so this suppresses a spurious log line rather than fixing swallowed signals. In pytest_plugin.py the removed except: raise was a pure no-op and the finally restoring AIRFLOW_CONFIG runs regardless, so removal is identical. Correct and cherry-pickable, just low impact. LGTM.