Cleanup `utilize_finding_data` feature flag
<!-- Title suggestion: [Feature flag] Cleanup <feature-flag-name> -->
## Summary
This issue is to cleanup the `utilize_finding_data` feature flag, after the feature flag has been enabled by default for an appropriate amount of time in production.
## Owners
- Team: ~"group::threat insights"
- Most appropriate slack channel to reach out to: `#g_govern_threat_insights`
- Best individual to reach out to: `@minac`
## Expectations
### Cleaning up the feature flag
<!-- The checklist here is to help stakeholders keep track of the feature flag status -->
- [x] Create a merge request to remove `utilize_finding_data` feature flag. Ask for review and merge it.
- [x] Remove all references to the feature flag from the codebase.
- [x] Remove the YAML definitions for the feature from the repository.
- [x] Create [a changelog entry](https://docs.gitlab.com/ee/development/feature_flags/#changelog).
- [x] Ensure that the cleanup MR has been deployed to both production and canary.
If the merge request was deployed before [the code cutoff](https://about.gitlab.com/handbook/engineering/releases/#self-managed-releases-1),
the feature can be officially announced in a release blog post.
- [x] `/chatops run auto_deploy status <merge-commit-of-cleanup-mr>`
- [x] If not already done, clean up the feature flag from all environments by running these chatops command in `#production` channel:
- [x] `/chatops run feature delete <feature-flag-name> --dev`
- [x] `/chatops run feature delete <feature-flag-name> --staging`
- [x] `/chatops run feature delete <feature-flag-name>`
- [ ] Close this rollout issue.
issue