Squish: Stabilize test for removal of break points

Change-Id: I1fdfc654e18a4cb219624b65e5d812faa479eb66
Reviewed-by: Robert Loehning <robert.loehning@qt.io>

tests/system/shared/debugger.py

@@ -111,6 +111,7 @@ def removeOldBreakpoints():
     except:
         test.fatal("UI seems to have changed - check manually and fix this script.")
         return False
+    waitFor("model.rowCount() == 0", 1000)
     return test.compare(model.rowCount(), 0, "Check if all breakpoints have been removed.")
 
 # function to do simple debugging of the current (configured) project