Reduce gitlab project import queries

This change reduces the number of DB queries when importing a gitlab
project.

app/models/application_record.rb

@@ -66,6 +66,12 @@ class ApplicationRecord < ActiveRecord::Base
     end
   end
 
+  def create_or_load_association(association_name)
+    association(association_name).create unless association(association_name).loaded?
+  rescue ActiveRecord::RecordNotUnique, PG::UniqueViolation
+    association(association_name).reader
+  end
+
   def self.underscore
     Gitlab::SafeRequestStore.fetch("model:#{self}:underscore") { self.to_s.underscore }
   end

app/models/project.rb

@@ -104,16 +104,13 @@ class Project < ApplicationRecord
 
   after_save :create_import_state, if: ->(project) { project.import? && project.import_state.nil? }
 
-  after_create :create_project_feature, unless: :project_feature
+  after_create -> { create_or_load_association(:project_feature) }
 
-  after_create :create_ci_cd_settings,
-    unless: :ci_cd_settings
+  after_create -> { create_or_load_association(:ci_cd_settings) }
 
-  after_create :create_container_expiration_policy,
-               unless: :container_expiration_policy
+  after_create -> { create_or_load_association(:container_expiration_policy) }
 
-  after_create :create_pages_metadatum,
-               unless: :pages_metadatum
+  after_create -> { create_or_load_association(:pages_metadatum) }
 
   after_create :set_timestamps_for_create
   after_update :update_forks_visibility_level

app/services/projects/create_service.rb

@@ -40,7 +40,7 @@ module Projects
       if namespace_id
         # Find matching namespace and check if it allowed
         # for current user if namespace_id passed.
-        unless allowed_namespace?(current_user, namespace_id)
+        unless current_user.can?(:create_projects, project_namespace)
           @project.namespace_id = nil
           deny_namespace
           return @project
@@ -83,13 +83,6 @@ module Projects
       @project.errors.add(:namespace, "is not valid")
     end
 
-    # rubocop: disable CodeReuse/ActiveRecord
-    def allowed_namespace?(user, namespace_id)
-      namespace = Namespace.find_by(id: namespace_id)
-      current_user.can?(:create_projects, namespace)
-    end
-    # rubocop: enable CodeReuse/ActiveRecord
-
     def after_create_actions
       log_info("#{@project.owner.name} created a new project \"#{@project.full_name}\"")