fix test.mig_settings for OIDC migrations and swappable dependencies?

[n2ygk]

Describe the bug
Apparently the document use of tests.mig_settings is OIDC additions per #1452 (comment)

Also it appears that swappable dependency instructions need to be added.

To Reproduce
TBD

Expected behavior
The documented instructions to add new migrations should work as expected.

Version
master branch

• I have tested with the latest published release and it's still a problem.
• I have tested with the master branch and it's still a problem.

Additional context