Fix T55178: Cursor fails to restore on cancel

574c0fe38f caused complications
restoring the cursor.

Use WM_cursor_modal_set/restore which is intended for operator use,
calling ED_region_cursor_set after an operator runs isn't reliable.

source/blender/windowmanager/intern/wm_event_system.c

@@ -1958,14 +1958,7 @@ static int wm_handler_operator_call(bContext *C, ListBase *handlers, wmEventHand
 
 				/* remove modal handler, operator itself should have been canceled and freed */
 				if (retval & (OPERATOR_CANCELLED | OPERATOR_FINISHED)) {
-					/* set cursor back to the default for the region */
-					wmWindow *win = CTX_wm_window(C);
-					WM_cursor_grab_disable(win, NULL);
-					/* Causes crash when joining areas: T55166, seems this is not even needed. */
-#if 0
-					ED_region_cursor_set(win, area, region);
-#endif
-
+					WM_cursor_grab_disable(CTX_wm_window(C), NULL);
 
 					BLI_remlink(handlers, handler);
 					wm_event_free_handler(handler);