Fixed #23740 -- Fixed removing unique_together constraint if exists primary key/unique constraint on the same field.

[David-Wobrock]

Hi,

Tackling ticket-23740.

In short:

1/ If the field is the primary key, fix it by filtering on "primary_key": False in django.db.backends.base.schema.BaseDatabaseSchemaEditor.alter_unique_together

2/ If the field has a unique=True constraint, to fix we check that the constraint name is the default one we would give to a unique_together constraint, based on the observation that a unique=True and a unique_together constraints are named differently at the time of writing

[felixxm]

@David-Wobrock Thanks 👍 I left comments.

[David-Wobrock]

Thanks for the review @felixxm 🙏
I amended and pushed the commit with the changes.

[felixxm]

@David-Wobrock Thanks 👍