Remove unnecessary validation avoiding N+1 queries

Remove unnecessary validation avoiding N+1 queries when building
integrations. This is a follow-up to fix
https://gitlab.com/gitlab-org/gitlab/-/issues/326209 where find or
initialize services causes N+1 queries.

Find or initialize the services has the following precedence:
- Find existing records.
- Build services from instance-level record or service template record.
  => This commit fixes the N+1 here.
- Build services from scratch. Fixed
  https://gitlab.com/gitlab-org/gitlab/-/merge_requests/58879.

In this case, when building one integration from an instance-level
integration or service template we check for service.invalid? which
triggers a query. service is an in-memory object but it checks the
uniqueness by type and project.  We can remove this because it's
redundant:
- All the integration records should be valid, we worked to verified
  that https://gitlab.com/groups/gitlab-org/-/epics/3366.
- build_from_integration copy the active value from the instance-level
  or service template. So if that integration is inactive,
  service = integration.dup will copy active attribute as false.

app/models/service.rb

@@ -241,7 +241,6 @@ class Service < ApplicationRecord
     service.project_id = project_id
     service.group_id = group_id
     service.inherit_from_id = integration.id if integration.instance? || integration.group
-    service.active = false if service.invalid?
     service
   end
 

changelogs/unreleased/326209-remove-unnecessary-validation.yml

+---
+title: Remove unnecessary validation avoiding N+1 queries when building integrations
+merge_request: 59635
+author:
+type: performance

spec/services/projects/create_service_spec.rb

@@ -273,16 +273,6 @@ RSpec.describe Projects::CreateService, '#execute' do
       opts[:default_branch] = 'master'
       expect(create_project(user, opts)).to eq(nil)
     end
-
-    it 'sets invalid service as inactive' do
-      create(:service, type: 'JiraService', project: nil, template: true, active: true)
-
-      project = create_project(user, opts)
-      service = project.services.first
-
-      expect(project).to be_persisted
-      expect(service.active).to be false
-    end
   end
 
   context 'wiki_enabled creates repository directory' do
@@ -633,17 +623,6 @@ RSpec.describe Projects::CreateService, '#execute' do
         end
       end
     end
-
-    context 'when there is an invalid integration' do
-      before do
-        create(:service, :template, type: 'DroneCiService', active: true)
-      end
-
-      it 'creates an inactive service' do
-        expect(project).to be_persisted
-        expect(project.services.first.active).to be false
-      end
-    end
   end
 
   context 'when skip_disk_validation is used' do