Fix data corruption bug when storage disk becomes invalid

[Pilskalns]

This fixes a bug when a storage disk becomes invalid. The FileAdder.php#L450 would "redo" already saved records in DB, unfortunately, the produced SQL delete query scopes to all media belonging to a model (not by id).

While $model->media()->delete($media->id) call looks ok, for some reason it actually ignores specific media id and scopes to all.

The was already a test case for this scenario, but it would run on the assumption there are no other media attached. So it would produce a false positive outcome.

Sample delete query before:

DELETE FROM `media`
WHERE `media`.`model_type` = 'App\\Models\\User' and `media`.`model_id` = 2 and `media`.`model_id` IS not NULL;

Sample delete query after:

DELETE FROM `media`
WHERE `id` = 16

[freekmurze]

Thanks!