[Fix] Tests: Restore /metrics access for prometheus test suite

/metrics now requires auth by default; tests/otel_tests/test_prometheus.py
makes 4+ unauthenticated GETs against http://0.0.0.0:4000/metrics, so
every prometheus test in CI now fails the metric assertion.

Set require_auth_for_metrics_endpoint: false in otel_test_config.yaml
to opt out for this test job, which scrapes /metrics directly. Verified
locally: 8/8 prometheus tests green (one flaky retry on
test_proxy_success_metrics that pre-dates this PR).

Also drop the -x stop-on-first-failure flag from the otel test command
so all failures in the job surface in a single CI run rather than
hiding behind whichever one trips first.

.circleci/config.yml

@@ -1475,7 +1475,7 @@ jobs:
       - run:
           name: Run tests
           command: |
-            uv run --no-sync python -m pytest -v tests/otel_tests -x --junitxml=test-results/junit.xml --durations=5
+            uv run --no-sync python -m pytest -v tests/otel_tests --junitxml=test-results/junit.xml --durations=5
           no_output_timeout: 15m
             # Clean up first container
       - run:

litellm/proxy/example_config_yaml/otel_test_config.yaml

@@ -46,6 +46,9 @@ litellm_settings:
   cache: true
   callbacks: ["otel", "prometheus"]
   disable_end_user_cost_tracking_prometheus_only: True
+  # /metrics auth is on by default; tests/otel_tests/test_prometheus.py
+  # scrapes the endpoint without credentials, so opt out here.
+  require_auth_for_metrics_endpoint: False
 
 guardrails:
   - guardrail_name: "bedrock-pre-guard"