temp: Restrict forum bulk-delete to global staff only

[kdmccormick]

This is one potential solution for:

• bulk_delete_user_posts REST API issues #37402

See that ^ issue for details and rationale.

This is a stop-gap solution so that the API can exist in Ulmo, but afterwards, we will either need to:

• add MySQL forum support to this API
• OR remove the API entirely

[kdmccormick]

@jristau1984 @e0d , here is one potential solution for the Forum Bulk-Delete REST API. It would keep the API as-is, but it would restrict it to global staff only. This is a stop-gap solution that would allow the REST API to continue existing in Ulmo, but without security concerns. In order to keep the REST API in the platform for Verawood, it would need to be retrofitted to support MySQL forums (in addition to MongoDB forums, which it currently supports).