Revisit logic for deleting grant-authorized records when handling a permission revocation `RecordsWrite`

[thehenrytsai]

Revisit logic in postProcessingForCoreRecordsWrite() for deleting grant-authorized records when handling a permission revocation RecordsWrite.

It appears that there was no test for it and it does not look like the code worked:

• not seeing permissionsGrantId being an index
• not seeing this.dataStore being called to delete actual data
• test coverage is missing for the main delete logic