Avoid external IP lookup for inproc addresses

[mmaxjr]

Fixes #8559.

This changes the inproc communication manager to use the loopback address as its local process identifier instead of calling get_ip(), which may try to discover a route to 8.8.8.8 and warn on offline machines. Since inproc addresses are only valid within the current process, no external IP discovery is needed.

Tests:

• python -m pytest distributed/deploy/tests/test_local.py::test_transports_inproc_does_not_discover_external_ip distributed/deploy/tests/test_local.py::test_transports_inproc distributed/deploy/tests/test_local.py::test_move_unserializable_data
• python -m pytest distributed/comm/tests/test_comms.py::test_get_address_host distributed/comm/tests/test_comms.py::test_get_local_address_for distributed/comm/tests/test_comms.py::test_inproc_client_server distributed/comm/tests/test_comms.py::test_inproc_addresses
• python -m ruff check distributed/comm/inproc.py

[github-actions]

Unit Test Results

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

    40 files  ± 0      40 suites  ±0   14h 37m 40s ⏱️ + 19m 58s
 4 161 tests + 1   3 981 ✅ ± 0    178 💤 ±0  2 ❌ +1 
80 981 runs  +22  76 738 ✅ +19  4 241 💤 +2  2 ❌ +1 

For more details on these failures, see this check.

Results for commit a4b5b64. ± Comparison against base commit dc182bd.

♻️ This comment has been updated with latest results.