Deprecate GitLabCiService making it to always be inactive

app/models/project_services/gitlab_ci_service.rb

@@ -18,6 +18,11 @@
 #  note_events           :boolean          default(TRUE), not null
 #
 
+# TODO(ayufan): The GitLabCiService is deprecated and the type should be removed when the database entries are removed
 class GitlabCiService < CiService
-  # this is no longer used
+  # We override the active accessor to always make GitLabCiService disabled
+  # Otherwise the GitLabCiService can be picked, but should never be since it's deprecated
+  def active
+    false
+  end
 end