Integration tests appear to fail despite green CI status

[tillsc]

The GitHub Actions workflow reports green status for integration tests, but the output suggests otherwise. Example:
https://github.com/jruby/warbler/actions/runs/15866068938/job/44733092626#step:7:1210

At the linked line, several tests clearly fail, yet the overall step and job are marked as successful. This might indicate that the integration test runner or script does not properly propagate exit codes or failures.