Since ExtJS 6.7, when a load of a store is cancelled by returning false into a on "beforeload" listener, the on "load" listeners are still called, whereas in ExtJS 6.5 it wasn't.

It could lead to some errors into on "load" listeners.

For a "load" potentially canceled by a "beforeload" listener, we now have to check the 3rd operation arguments and test its "aborted" property. If operation.aborted is true, do nothing.