Docker: give the worker time to finish a paid call on stop (#3)

The worker waits up to 195 s (STOP_TIMEOUT_MS) for a paid call in flight, but Docker
sends SIGKILL 10 s after SIGTERM by default, so every deploy could cut a call off and
leave an "outcome unknown" receipt that is paid for again later.

Co-authored-by: lucky-Luor <173367625+lucky-Luor@users.noreply.github.com>