Revert running migration specs against both DBs

What does this MR do and why?

Designed to revert !118234 (merged) to fix #412081 (closed) . This migration doubled the amount of time needed for migration specs. Then I also found that !120998 (merged) was dependent on the MR I'm trying to revert so I, unfortunately, had to revert that too.

1. Revert "Merge branch 'jp-embedd-mig' into 'master'"
   • This reverts commit 4b6ddfee, reversing changes made to fc5baccc.
2. Revert "Merge branch 'rw-specs-db-migrations-run-on-both' into 'master'"
   • This reverts commit efeee9ee, reversing changes made to 2cbab36e.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #412081 (closed)