Pass user instance to Labels::FindOrCreateService or skip_authorization: true
## What does this MR do?
It fixes a bug described in #23694 when `project.owner` was passed to `Labels::FindOrCreateService`. `Labels::FindOrCreateService` expected a user instance and `project.owner` may return a group as well. This MR makes sure that we either pass a user instance or `skip_authorization: true`.
## Are there points in the code the reviewer needs to double check?
- places where we pass `skip_authorization: true`
## Does this MR meet the acceptance criteria?
- Tests
- [x] Added for this feature/bug
- [ ] All builds are passing
- [ ] Conform by the [merge request performance guides](http://docs.gitlab.com/ce/development/merge_request_performance_guidelines.html)
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if it does - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)
## What are the relevant issue numbers?
Fixes#23694
See merge request !7093
While Octokit auto pagination set the page size to the maximum 100, and
seek to not overstep the rate limit. When the rate limit is reached its
raises an exception, and stop doing new requests.
Here we use a custom pattern for traversing large lists, so we can
check if we’ll reach the rate limit and wait the API to reset the rate
limit before making new requests.
Douwe Maan