Merge branch 'refactor-create-service-spec' into 'master'

Refactor create service spec

## What does this MR do?
Use let instead instance variables to cache create user operation.

Union some example into one.

## Are there points in the code the reviewer needs to double check?

## Why was this MR needed?
Time before: 1 minute 11.81 seconds

Time after: 52.47 seconds

- [x] [Changelog entry](https://docs.gitlab.com/ce/development/changelog.html) added
- n/a [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- n/a API support added
- Tests
  - n/a Added for this feature/bug
  - [x] All builds are passing
- [x] 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?

See merge request !7609

0 files changed, 0 insertions, 0 deletions