Account deletion task had a bug in it: its was skipping all accounts
that were deactivated, but accounts are deactivated as soon as
date_deletion_requested is received via webhook, so no
deletion/anonymisation would have happened.
In addition to fixing that (now the task will exclude all account records
that look like they were already anonymized), this also changes several on-delete properties:
* abuse reports about a deleted account are deleted along with it;
* abuse reports made by a deleted account remain;
* ratings made by a deleted account remain;
* approval activity protects against deletion: account cannot be deleted if it authored any approval activity;
This change also makes sure that API tokens and OAuth info/tokens
are deleted when account deleted or anonymized.
Anna Sirota
729ce453ac