ci: run tests with 2 second http timeout (#18529)

## Description

Reduce Test Optimization API requests' timeout to 2 seconds, to avoid CI jobs from timing out when responses are slow.

## Testing

<!-- Describe your testing strategy or note what tests are included -->

## Risks

<!-- Note any risks associated with this change, or "None" if no risks -->

## Additional Notes

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Co-authored-by: federico.mon <federico.mon@datadoghq.com>

Author: gnufede

riotfile.py

@@ -97,6 +97,7 @@ def select_pys(min_version: str = MIN_PYTHON_VERSION, max_version: str = MAX_PYT
     "DD_PYTEST_USE_NEW_PLUGIN": "true",
     "DD_TRACE_COMPUTE_STATS": "false",
     "DD_CODE_ORIGIN_FOR_SPANS_ENABLED": "false",
+    "DD_CIVISIBILITY_BACKEND_API_TIMEOUT_MILLIS": "2000",  # 2-second timeout
     # Enable out-of-session retries for dd-trace-py's own test runs (opt-in feature) so state-leaking flaky tests get a
     # clean-slate retry. Only acts on ATR-exhausted failures. See ddtrace/testing/internal/pytest/plugin.py.
     "_DD_CIVISIBILITY_OUT_OF_SESSION_RETRIES_ENABLED": "1",

tests/testing/internal/test_http.py

@@ -29,7 +29,12 @@ class TestBackendConnector:
 
     def test_constants(self) -> None:
         """Test module constants."""
-        assert DEFAULT_TIMEOUT_SECONDS == 30.0
+        # Verify the parsing function returns the correct default when no env var is set
+        assert _http_module._parse_timeout_millis(None) == 30.0
+        # Verify the module constant matches what it should be for the current environment
+        # (may be overridden if env var was set at module import time)
+        expected = _http_module._parse_timeout_millis(os.environ.get("DD_CIVISIBILITY_BACKEND_API_TIMEOUT_MILLIS"))
+        assert DEFAULT_TIMEOUT_SECONDS == expected
 
     @patch("http.client.HTTPSConnection")
     def test_init_default_parameters(self, mock_https_connection: Mock) -> None: