Migrate old data to new PostgreSQL architecture
About
After #213776 new changes to Design Management have been recorded in the new PostgreSQL architecture #213772 as well as legacy.
In order to switch the application over to read its data from the new architecture we need to backfill data.
The data migration should be done according to our background migrations developer docs.
Once migrated, we can begin adjusting the application to read from the new architecture.
Note ideally we do this issue in the same release as #213751 for reasons given in that issue.
Issue was refined in #240691 (closed).
Permissions and Security
None.
Documentation
None.
Availability & Testing
Tests of the background migration.
Recommended MR Breakdown
1 MR.
Edited by Luke Duncalfe