What does this MR do?
Use the ruby 2.3.5 containers
Does this MR meet the acceptance criteria?
Changelog entry added, if necessary
- [-] API support added
- [-] Tests added for this feature/bug
- [-] Has been reviewed by UX
- [-] Has been reviewed by Frontend
Has been reviewed by Backend
- [-] Has been reviewed by Database
- [-] Conform by the merge request performance guides
- [-] Conform by the style guides
- [-] Squashed related commits together
part of: gitlab-org/gitlab-ce#38040