Refactor deprovision and facility deletion utilities to share code

[rtibbles]

We currently have two sets of utilities that attempt to completely hard delete a facility and all related metadata - due to the complexity of this task, and the history of bugs we have seen in it, it would be wise to attempt to unify the functionality where possible, to ensure that there is no duplication that might lead to bugs in one utility vs another.

I forget if we've discussed this before, but should we be consolidating the deprovision command with the other deletion utilities for deleting a Facility? https://github.com/learningequality/kolibri/blob/develop/kolibri/core/auth/utils/delete.py

It does seem like there would be some room to refactor in order to share code, yeah.

Originally posted by @jamalex in https://github.com/learningequality/kolibri/issues/9208#issuecomment-1089227622