Investigate `x509_forced_cert_loading` feature flag
<!--IssueSummary start-->
<details>
<summary>
Everyone can contribute. [Help move this issue forward](https://handbook.gitlab.com/handbook/marketing/developer-relations/contributor-success/community-contributors-workflows/#contributor-links) while earning points, leveling up and collecting rewards.
</summary>
- [Close this issue](https://contributors.gitlab.com/manage-issue?action=close&projectId=278964&issueIid=506033)
</details>
<!--IssueSummary end-->
### Problem
Feature flag `x509_forced_cert_loading` is disabled on GitLab.com.
It's not clear if the original problem still exists and if the fix is safe to apply.
### Proposal
Review the original problem and try to test the fix behind the feature flag.
Possible outcomes:
* Proceed with a feature flag rollout
* Remove the feature flag and code behind it
issue