Creating new records has been disabled, and all
existing records been migrated to clusters as of
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/28534

We are deprecating this service in favor of instance wide clusters.
Therefore we removed some code that is not anymore needed for a
readonly cluster and also we added some flags to allow for this
deprecation. These flags are to be removed in the next release when
we finally completelly remove KubernetesService.

Rename btn-new, btn-create and btn-save to btn-success
Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

`breadcrumb_title` is then overriden when needed

split field logic to separate template.

Closes #1275