Fix flaky test_include_communication_in_occupancy

[gjoseph92]

This assertion would sometimes fail, and occ3 would be some number like 0.020008087158203125

distributed/distributed/tests/test_scheduler.py

Lines 1506 to 1507 in 581b603

	# Occ should be 2 * 0.5 (CPU, unknown)
	assert occ3 == 1

On slower CI (macOS), the worker would have a chance to heartbeat before that line, updating the max_exec_time. When the duration average is unknown but the max_exec_time is known, we use that to calculate occupancy.

Adding an await asyncio.sleep(0.5) above that line was a reliable way to make the test always fail.

• Tests added / passed
• Passes pre-commit run --all-files

[github-actions]

Unit Test Results

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

       15 files  ±0         15 suites  ±0   6h 41m 20s ⏱️ + 14m 36s
  3 160 tests ±0    3 074 ✔️ +1    83 💤 ±0  3 ❌  - 1 
23 380 runs  ±0  22 476 ✔️ +3  900 💤 +1  4 ❌  - 4 

For more details on these failures, see this check.

Results for commit 3fae185. ± Comparison against base commit 581b603.

[hendrikmakait]

EDIT: This was meant to be an approval.

[hendrikmakait]

LGTM, thanks @gjoseph92!