Email Reminder Job - Remove/Cleanup old versioning DB artifacts

After PROD deployment of new DB versioning and if things have been looking good for a while, we want to start removing the code for the old versioning.

That also includes the removal of usage of the feature flags from the code. We will only use the code for the new versioning.

We will keep the feature flags in LD for now. We can remove later once all the cleanup is done.

This ticket takes care of the email reminder job cleanup.

Need to handle:
- [ ] Clean the old DB artifacts from the email reminder job
- [ ] Might need some additional misc. tweaks/removals
- [ ] Verify/test your changes and monitor if something's missing

Locate the email reminder job and trace its old DB-versioning and feature-flag references. Review the related tests and run the job's verification checks before removing the obsolete artifacts and code usage; done means the new versioning path remains intact, tests pass, and the retained LD flags are still handled as specified.

Written by the indexing model from the issue text.