VSE: Remove delete confirmation pop-up

It is not needed with the current undo system.

Differential Revision: https://developer.blender.org/D7807

source/blender/editors/space_sequencer/sequencer_edit.c

@@ -2508,7 +2508,7 @@ static int sequencer_delete_invoke(bContext *C, wmOperator *op, const wmEvent *e
     }
   }
 
-  return WM_operator_confirm(C, op, event);
+  return sequencer_delete_exec(C, op);
 }
 
 void SEQUENCER_OT_delete(wmOperatorType *ot)