[Task]: Force migrations that execute python code to run on primary database

[diox]

Description

Database migrations that use RunPython use the regular database routing rules, which means reads to to the replica.

So you can create a situation where a migration adds some data, then the following migration after that attempts to read that data and fails because it's using the replica which doesn't have it yet.

We would try to monkeypatch RunPython to force the primary db to be used, or have our own function that does it and force us to use it instead of the original through some linting.

See also #15559

Acceptance Criteria

• RunPython migrations use the primary db somehow

┆Issue is synchronized with this Jira Task

[diox]

Happened on stage recently: #16068