GitLab

Defer saving project services to the database if there are no user changes

## What does this MR do?

It defers saving project services to the database as long as it is possible. It creates a project service when creating a project only if this project service has an active template. After that project services are saved on the first edit.

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

- tests that used `build_missing_services` before the change
- number of queries executed

## Why was this MR needed?

Motivation in #22281

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] 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?

Fixes #22281

See merge request !6958