Speed up test_semaphore.py

[fjetter]

Depends on #5883

Closes #6190

[github-actions]

Unit Test Results

       12 files  ±0         12 suites  ±0   5h 50m 52s ⏱️ - 1m 25s
  2 653 tests ±0    2 571 ✔️ +1    80 💤 ±0  2 ❌  - 1 
13 021 runs  ±0  12 382 ✔️ +2  636 💤  - 1  3 ❌  - 1 

For more details on these failures, see this check.

Results for commit 8e4f542. ± Comparison against base commit 7a69b5e.

♻️ This comment has been updated with latest results.

[fjetter]

test_timeout_zero also appears to fail occasionally with a tornado exception indicating that the PeriodicCallback._run was never awaited. Since we only see this very rarely, I suspect this is because we're not actually stopping the callback.

The test_release_future was merely a race condition. I removed all the log asserts since this kind of instrumentation is actually not necessary for this.

The other changes speed up test runtime a bit

[github-actions]

Unit Test Results

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

       22 files  ±0         22 suites  ±0   9h 37m 16s ⏱️ +2s
  3 288 tests +1    3 201 ✔️ +3       85 💤  - 1  1 ❌  - 2  1 🔥 +1 
36 089 runs  +1  34 527 ✔️ +3  1 560 💤  - 1  1 ❌  - 2  1 🔥 +1 

For more details on these failures and errors, see this check.

Results for commit 8f04c42. ± Comparison against base commit b5a2078.