Removed special handling of part files in shared storage rename

This fixes the issue introduced by the transfer id which itself wasn't
taken into account by the shortcut code for part file in the shared
storage class.
Merge pull request #6687 from owncloud/sharing-fixpartfilehandling

Removed special handling of part files in shared storage rename
Merge branch 'master' into update-sabre-2.0

Conflicts:
	lib/private/connector/sabre/file.php