test(python): wait for thread state in tcpip server interface tests

[EmilyRagan]

What changed

Replaced the fixed time.sleep() calls that precede thread-dependent assertions in openc3/python/test/interfaces/test_tcpip_server_interface.py with the existing wait_for polling helper from test/test_helper.py.

Affected assertions:

• test_server_read_only / test_read_and_write - read_queue_size() == 1
• test_multiple_connections - num_clients() == 1 and == 0 after closing sockets
• test_first_read_client_disconnect_cleans_up - num_clients() == 1 and len(read_interface_infos) == 0

Why it changed

test_server_read_only failed on Python 3.12 in https://github.com/OpenC3/cosmos/actions/runs/36072084541/attempts/1 (PR #3897, unrelated change):

test/interfaces/test_tcpip_server_interface.py:132: in test_server_read_only
    self.assertEqual(i.read_queue_size(), 1)
E   AssertionError: 0 != 1

The test sends bytes to the server socket and then sleeps 0.1s before asserting that the read thread has queued a packet. 0.1s is comfortable on a developer machine but not guaranteed on a loaded CI runner, so the assertion races the thread. The other sleeps in this file sit in front of the same kind of assertion, so they are fixed together rather than waiting for each to fail on its own.

wait_for polls at 5ms up to a 5s timeout and does not assert on timeout, so the caller's original assertion still produces the failure message.

Testing strategy

uv run pytest test/interfaces/test_tcpip_server_interface.py run 5 times locally, 19 passed each time. Runtime dropped from ~3.2s to ~0.9s since polling returns as soon as the condition holds instead of always sleeping the full interval. ruff check and ruff format --check clean.

Review notes

Test-only change; no production code touched. Sleeps that only pace a blocking sock.recv() are left alone - recv blocks until data arrives, so they are not racing an assertion.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.07%. Comparing base (ef52d2a) to head (8a5b1a7).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3940      +/-   ##
==========================================
+ Coverage   80.05%   80.07%   +0.01%     
==========================================
  Files         901      901              
  Lines       68355    68355              
  Branches     2645     2698      +53     
==========================================
+ Hits        54722    54732      +10     
+ Misses      12961    12950      -11     
- Partials      672      673       +1     

Flag	Coverage Δ
frontend	66.67% <ø> (+0.04%)	⬆️
python	80.11% <ø> (+<0.01%)	⬆️
ruby-api	82.61% <ø> (+0.06%)	⬆️
ruby-backend	85.65% <ø> (ø)

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud