Use IO task marker in scheduling

[jrbourbeau]

Companion PR to dask/dask#11558 where we incorporate the new io_task attribute into our scheduling logic

[github-actions]

Unit Test Results

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

    27 files  ±    0      27 suites  ±0   11h 49m 51s ⏱️ + 54m 0s
 4 113 tests  -     1   3 998 ✅ +    1    111 💤  -  2  4 ❌ +1 
51 576 runs  +1 421  49 283 ✅ +1 385  2 289 💤 +38  4 ❌  - 1 

For more details on these failures, see this check.

Results for commit 67e6e04. ± Comparison against base commit 0657de2.

This pull request removes 2 and adds 1 tests. Note that renamed tests count towards both.

distributed.cli.tests.test_dask_worker.test_listen_address_ipv6[tcp:..[ ‑ 1]:---nanny]
distributed.cli.tests.test_dask_worker.test_listen_address_ipv6[tcp:..[ ‑ 1]:---no-nanny]

distributed.tests.test_scheduler ‑ test_data_producers

♻️ This comment has been updated with latest results.