Clean up deprecations in distributed.deploy

[crusaderky]

Note: this PR does not clean up old_ssh. This is because it is still used by dask ssh, and changing the CLI to use the new SSHCluster would be a much more substantial change.

[github-actions]

Unit Test Results

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

    30 files  ±  0      30 suites  ±0   10h 57m 41s ⏱️ -49s
 4 106 tests  -   9   4 000 ✅  -  9    104 💤 ± 0  2 ❌ ±0 
59 641 runs   - 114  57 233 ✅  - 79  2 405 💤  - 36  3 ❌ +1 

For more details on these failures, see this check.

Results for commit d72598d. ± Comparison against base commit efb2a7d.

This pull request removes 9 tests.

distributed.deploy.tests.test_local ‑ test_threads_per_worker_set_to_0
distributed.deploy.tests.test_old_ssh ‑ test_extra_kwargs_is_an_error
distributed.deploy.tests.test_old_ssh ‑ test_nprocs_attribute_is_deprecated
distributed.deploy.tests.test_old_ssh ‑ test_old_ssh_n_workers_with_nprocs_is_an_error
distributed.deploy.tests.test_old_ssh ‑ test_old_ssh_nprocs_renamed_to_n_workers
distributed.deploy.tests.test_spec_cluster ‑ test_logs_deprecated
distributed.deploy.tests.test_ssh ‑ test_nprocs_attribute_is_deprecated
distributed.deploy.tests.test_ssh ‑ test_ssh_n_workers_with_nprocs_is_an_error
distributed.deploy.tests.test_ssh ‑ test_ssh_nprocs_renamed_to_n_workers

♻️ This comment has been updated with latest results.