Bugfix: Do not try to delete the folder twice

Previously, when a folder was moved to the trashbin from an external storage, the usual

action was to copy the contents to the trashbin and then remove them from the source, and

additionally another remove operation on the source was triggered. This second delete

request was performed but the result was ignored, and the storages didn't log anything.

With this change, this second delete request won't happen. The behaviour is still the same:

copy to the trashbin and then remove from the source.

https://github.com/owncloud/core/pull/39070