Remove FDW related code for container repositories

Since GitLab 13.2 we don't rely on FDW queries
to sync these repositories.

ee/app/models/geo/fdw/container_repository.rb

-# frozen_string_literal: true
-
-module Geo
-  module Fdw
-    class ContainerRepository < ::Geo::BaseFdw
-      self.table_name = Gitlab::Geo::Fdw.foreign_table_name('container_repositories')
-      self.primary_key = :id
-
-      belongs_to :project, class_name: 'Geo::Fdw::Project', inverse_of: :container_repositories
-
-      scope :project_id_in, ->(ids) { joins(:project).merge(Geo::Fdw::Project.id_in(ids)) }
-
-      class << self
-        def inner_join_container_repository_registry
-          join_statement =
-            arel_table
-              .join(container_repository_registry_table, Arel::Nodes::InnerJoin)
-              .on(arel_table[:id].eq(container_repository_registry_table[:container_repository_id]))
-
-          joins(join_statement.join_sources)
-        end
-
-        def missing_container_repository_registry
-          left_outer_join_container_repository_registry
-            .where(container_repository_registry_table[:id].eq(nil))
-        end
-
-        private
-
-        def container_repository_registry_table
-          Geo::ContainerRepositoryRegistry.arel_table
-        end
-
-        def left_outer_join_container_repository_registry
-          join_statement =
-            arel_table
-              .join(container_repository_registry_table, Arel::Nodes::OuterJoin)
-              .on(arel_table[:id].eq(container_repository_registry_table[:container_repository_id]))
-
-          joins(join_statement.join_sources)
-        end
-      end
-    end
-  end
-end

ee/app/models/geo/fdw/project.rb

@@ -8,8 +8,6 @@ module Geo
       self.primary_key = :id
       self.table_name = Gitlab::Geo::Fdw.foreign_table_name('projects')
 
-      has_many :container_repositories, class_name: 'Geo::Fdw::ContainerRepository'
-
       belongs_to :namespace, class_name: 'Geo::Fdw::Namespace'
 
       alias_method :parent, :namespace

ee/spec/models/geo/fdw/container_repository_spec.rb

-# frozen_string_literal: true
-
-require 'spec_helper'
-
-RSpec.describe Geo::Fdw::ContainerRepository, :geo, type: :model do
-  context 'relationships' do
-    it { is_expected.to belong_to(:project).class_name('Geo::Fdw::Project') }
-  end
-end

ee/spec/models/geo/fdw/project_spec.rb

-# frozen_string_literal: true
-
-require 'spec_helper'
-
-RSpec.describe Geo::Fdw::Project, :geo_fdw, type: :model do
-  context 'relationships' do
-    it { is_expected.to have_many(:container_repositories).class_name('Geo::Fdw::ContainerRepository') }
-  end
-end