Revert CICharField deprecation

[Johannes Maron]

Ref #33872 - ​https://github.com/django/django/commit/cb791a2540c289390b68a3ea9c6a79476890bab2

In case my mailing list comment gets lost, I make this as unreviewed and leave a copy here:
Hi there,

I am sorry that I missed this in the alpha. But to the best of my knowledge, CITEXT and non-deterministic collations are not the same. They don't support the same operations and their string comparison operations are similar, yet not identical.
Furthermore, PostgreSQL doesn't discourage the use of CITEXT, but hints towards a native alternative. That's maybe more than just a subtle difference.

99% of all use-cases might be email, but even email LIKE-queries would be affected (good for +-searches).
Unless we want to drop support for the CITEXT extension, collations might not be a sufficient replacement.

I'd caution to revert the deprecation and keep support unless we make an informed decision to drop CITEXT for a 3rd party integration.

Best
Joe!

Update: We noticed vast problems while trying to migrate to collations in Django admin. Sadly, this isn't straightforward and requires a lot of, which solidifies my belief that we should revert the deprecation altogether. Especially since the PG feature has no plans for discontinuation.

I really appreciate the effort that was put into the initial commit. But, weighting the user pain vs the rather marginal maintenance effort of the DB type, seems maybe not worth it.

[Mariusz Felisiak]

Thanks Joe, unfortunately, I'm forced to close it as "wontfix" based on current replies on the ​mailing list. We can reconsider this decision when there are more replies in favor of revert or we reach a consensus.

I hope that makes sense.