Fix ingress SSL configuration: passthrough bungles stats

Currently ssl is configured as passthrough; this hampers statistics because all requests are logged as coming from the ingress (and not from the original IP).

ToDos

• check with dspace-people how to use X-Real-IP and X-Forwarded-For headers in org.dspace.app.xmlui.utils.AuthenticationUtil
• once done, check whether commit 9717f5b1 from #44 (closed) can be reverted

Notes

Together with Luca we can come up with an alternative setup: The ingress controller is set to propagate the X-Real-IP and X-Forwarded-For headers.

Furthermore, we disabled the ssl-passthrough configuration, configured ssl on the ingress controller and https:// for the kube-internal communication.