`ahabd` supervision tests

[goodboy]

We kinda started some basic startup tests in #464 and #483 but we need a much more thorough list particularly for verifying we never leak container instances..

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Test list:

• [ ] basic connect tests (which pretty much exist in tests/test_databases.py but more generally for ahabd and some lighter container? say just running sshd 😉
• [ ] cancellation tests where the container either crashes or is explicitly cancelled
  • [ ] ctrl-c by user cases
  • [ ] maybe a respawn case as well like is needed with the ib and IBC restart every night thinger?
• [ ] a network failure test using maybe toxyproxy?
• [ ] verification of the log processing correctness even in error cases?