The server_name parameter of the "Delete media by date and size" is unused and confusing

[babolivier]

The "Delete media by date and size" admin API takes a server_name parameter. This makes it look like we only delete media that were uploaded to the local media repository. However, we only use it to check that it matches the local server's name:

synapse/synapse/rest/admin/media.py

Lines 318 to 319 in 3dd175b

	if self.server_name != server_name:
	raise SynapseError(HTTPStatus.BAD_REQUEST, "Can only delete local media")

We then proceed to call delete_old_local_media, which, confusingly, deletes local media and local copies of remote media. So remote media is deleted even when the server_name parameter is set to the local server.

[dklimpel]

Dup

• Delete Local Media Admin APIs unnecessarily requires specifying local server_name #9284

[clokep]

duplicates #9284.