Add support to the endpoint slice mirroring controller to mirror
annotations, in addition to labels, but don´t mirror endpoint
triggertime annotation.
Also, fix a bug in the endpointslice mirroring controller, that
wasn't updating the mirrored slice with the new labels, in case
that only the endpoint labels were modified.
The KEP specifies that the controller will "mirror all labels from the
Endpoints resource and all endpoints and ports from the corresponding subset".
I'd missed that in my initial implementation, this should fix that.
