[Feature flag] Cleanup vulnerabilities_as_webhook_events

Summary

This issue is to cleanup the vulnerabilities_as_webhook_events feature flag, after the feature flag has been enabled by default for an appropriate amount of time in production.

Related:

• [Feature flag] Rollout of `vulnerabilities_as_w... (#499996 - closed)
• Add vulnerabilities as supported webhook events (#366770 - closed)

Owners

• Team: ~"team::Product Security Engineering"
• Most appropriate slack channel to reach out to: #sec-product-security-engineering
• Best individual to reach out to: @ashmckenzie
• PM: N/A

Stakeholders

Expectations

What might happen if this goes wrong?

Cleaning up the feature flag

• Specify in the issue description if this feature will be removed completely or will be productized as part of the Feature Flag cleanup
• Create a merge request to remove vulnerabilities_as_webhook_events feature flag. Ask for review and merge it.
  • Remove all references to the feature flag from the codebase.
  • Remove the YAML definitions for the feature from the repository.
  • Create a changelog entry.
• Ensure that the cleanup MR has been deployed to both production and canary. If the merge request was deployed before the code cutoff, the feature can be officially announced in a release blog post.
  • /chatops run auto_deploy status bed4a2fa3e7b1abee4862ba7abdebb235351f602
• Close the feature issue to indicate the feature will be released in the current milestone.
• If not already done, clean up the feature flag from all environments by running these chatops command in #production channel: /chatops run feature delete vulnerabilities_as_webhook_events --dev --pre --staging --staging-ref --production
• Close this rollout issue.