Show a delete icon on the manual classification rejection button

From this thread on !596 (merged):

!596 (merged) adds a notification to warn the user that the manual classification they just rejected triggered a deletion, since rejecting manual classifications cause deletions. It could be possible to instead show a trashcan icon, just like what is already done for the element or metadata deletion buttons, to differentiate between rejecting (an X) and deleting, therefore warning the user before they click.