Fix all Django system check warnings in the Review Board codebase.
Review Request #11071 — Created July 6, 2020 and submitted
Django had a few warnings about code deprecations and recommendations,
which it would show every time the dev server loaded, or when running
other certain management commands.
This change satisfies all warnings (aside from one category, which is
silenced). This just consists of removing
ManyToManyFields(which doesn't do anything), and fully removing the
settings.TEMPLATE_*settings in favor of
The silenced warning is just a suggestion to change a
OneToOneField. This makes sense, but would require
new work in Django Evolution to understand the equivalency of this
change, and is not worth the time. So instead, we're just telling Django
to ignore this warning.
Ran some standard tests in Review Board. Didn't see any issues, or any
Unit tests pass.