Fix CI integration test rate limiting

- Add auth_intensive marker for tests that make many login requests
- Mark all tests in test_auth_api.py with auth_intensive
- Exclude auth_intensive tests from CI integration runs against deployed
  environments (they trigger 429 rate limiting)
- Remove duplicate TestSecurityEdgeCases class definition
- Register auth_intensive, integration, large, slow markers in conftest.py

.gitlab-ci.yml

@@ -52,12 +52,13 @@ kics:
     - pip install --index-url "$PIP_INDEX_URL" pytest pytest-asyncio httpx
   script:
     - cd backend
-    # Run full integration test suite, excluding large/slow tests
+    # Run full integration test suite, excluding large/slow tests and auth-intensive tests
+    # Auth-intensive tests make many login requests which trigger rate limiting on deployed environments
     # ORCHARD_TEST_URL tells the tests which server to connect to
     - |
       python -m pytest tests/integration/ -v \
         --junitxml=integration-report.xml \
-        -m "not large and not slow" \
+        -m "not large and not slow and not auth_intensive" \
         --tb=short
   artifacts:
     when: always