Remove apicast_v2 and apicast_oidc from rolling updates

These options are enabled by default now.
As suggested by Hery in https://github.com/3scale/zync/pull/142#discussion_r264275053
We should completely remove them from the code and not make them configurable anymore.
Then it can be removed also from the instructions in Zync and from the Deploy repository.

Dev Notes

cucumber tests
refactoring