Should the `WithPagination` concern raise errors on non-paginatable resources
As discussed with @grzesiek in https://gitlab.com/gitlab-org/gitlab-ce/commit/ca538899b66a6a82582d2d590297cfef1d310dcf#note_74839754:
When you currently call .with_pagination
on a serializer that represents an un-paginatable resource (a single instance, or an array that can't be paginated) we don't let Gitlab::Serializer::Pagination
raise an error.
This logic was copied over from the GroupSerializer
which doesn't seem used anymore.