Revert "[1.7.x] Undocumented SeparateDatabaseAndState so crash is not RB. Refs #22918"

Much like :class:`RunSQL`, ensure that if you change schema inside here you're

either doing it outside the scope of the Django model system (e.g. triggers)

or that you use a custom Operation to reflect your changes to the model

state - otherwise, the versioned ORM and the autodetector will stop

working correctly.

or that you use :class:`SeparateDatabaseAndState` to add in operations that will

reflect your changes to the model state - otherwise, the versioned ORM and

the autodetector will stop working correctly.

By default, ``RunPython`` will run its contents inside a transaction even

on databases that do not support DDL transactions (for example, MySQL and

    ``schema_editor.connection.alias``, where ``schema_editor`` is the second

    argument to your function).

SeparateDatabaseAndState

------------------------

.. class:: SeparateDatabaseAndState(database_operations=None, state_operations=None)

A highly specialized operation that let you mix and match the database

(schema-changing) and state (autodetector-powering) aspects of operations.

It accepts two list of operations, and when asked to apply state will use the

state list, and when asked to apply changes to the database will use the database

list. Do not use this operation unless you're very sure you know what you're doing.

Writing your own

================