While AlterUniqueTogether has been documented to be still allowed in historical
migrations for the foreseeable future it has been crashing since 2abf417c81
was merged because the latter removed support for Meta.index_together which the
migration framework uses to render models to perform schema changes.
CreateModel(options["unique_together"]) was also affected.
Refs #27236.
Co-authored-by: Simon Charette <charette.s@gmail.com>
