Fix exit code checking in tests/test_webhook_feature.sh

[gkapetanakis]

Summary

This PR fixes error handling in the webhook integration test script so test failures are reported explicitly instead of exiting early due to shell strict mode (set -e).

File changed:

• tests/test_webhook_feature.sh

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added/updated unit tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes