Merge branch 'adam-build-missing-services-when-necessary' into 'master'

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

1 files changed, 1 insertions, 16 deletions

diff --git a/lib/api/helpers.rb b/lib/api/helpers.rb
index 6998b6dc039..84cc9200d1b 100644
--- a/lib/api/helpers.rb
+++ b/lib/api/helpers.rb
@@ -86,25 +86,10 @@ module API
     end
 
     def project_service
-      @project_service ||= begin
-        underscored_service = params[:service_slug].underscore
-
-        if Service.available_services_names.include?(underscored_service)
-          user_project.build_missing_services
-
-          service_method = "#{underscored_service}_service"
-
-          send_service(service_method)
-        end
-      end
-
+      @project_service ||= user_project.find_or_initialize_service(params[:service_slug].underscore)
       @project_service || not_found!("Service")
     end
 
-    def send_service(service_method)
-      user_project.send(service_method)
-    end
-
     def service_attributes
       @service_attributes ||= project_service.fields.inject([]) do |arr, hash|
         arr << hash[:name].to_sym