Fix test nanny timeout

[fjetter]

This should be fixing distributed.tests.test_nanny.test_nanny_timeout which appears to be caused by a race condition between startup and kill.

That condition is now tested in a dedicated test test_worker_start_exception_while_killing

[github-actions[bot]]

Unit Test Results

See test report for an extended history of previous test failures. This is useful for diagnosing flaky tests.

    25 files  ± 0      25 suites  ±0   10h 9m 45s :stopwatch: - 7m 53s  4 125 tests + 3   4 008 :white_check_mark: + 3    111 :zzz: ±0  6 :x: +1  47 651 runs  +35  45 540 :white_check_mark: +37  2 105 :zzz:  - 2  6 :x: +1 

For more details on these failures, see this check.

Results for commit a3252530. ± Comparison against base commit ac7a24e8.

This pull request removes 1 and adds 4 tests. Note that renamed tests count towards both.

distributed.tests.test_nanny ‑ test_nanny_timeout

distributed.tests.test_nanny ‑ test_nanny_restart
distributed.tests.test_nanny ‑ test_nanny_restart_timeout
distributed.tests.test_nanny ‑ test_nanny_restart_timeout_stress
distributed.tests.test_nanny ‑ test_worker_start_exception_while_killing

:recycle: This comment has been updated with latest results.

[fjetter]

This still has a problem...

[hendrikmakait]

This still has a problem...

Alright, just let me know once it's ready for a final review. CI looked good though 🙈

[fjetter]

@hendrikmakait should be good to go now