Remove Geo::Fdw::GeoNodeNamespaceLink model

Since GitLab 13.2 we don't rely on FDW query/models

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

@@ -8,8 +8,6 @@ module Geo
       self.table_name = Gitlab::Geo::Fdw.foreign_table_name('geo_nodes')
 
       serialize :selective_sync_shards, Array # rubocop:disable Cop/ActiveRecordSerialize
-
-      has_many :geo_node_namespace_links, class_name: 'Geo::Fdw::GeoNodeNamespaceLink'
     end
   end
 end

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

-# frozen_string_literal: true
-
-module Geo
-  module Fdw
-    class GeoNodeNamespaceLink < ::Geo::BaseFdw
-      self.table_name = Gitlab::Geo::Fdw.foreign_table_name('geo_node_namespace_links')
-
-      belongs_to :geo_node, class_name: 'Geo::Fdw::GeoNode', inverse_of: :namespaces
-    end
-  end
-end

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

-# frozen_string_literal: true
-
-require 'spec_helper'
-
-RSpec.describe Geo::Fdw::GeoNodeNamespaceLink, :geo, type: :model do
-  context 'relationships' do
-    it { is_expected.to belong_to(:geo_node).class_name('Geo::Fdw::GeoNode').inverse_of(:namespaces) }
-  end
-end

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

-# frozen_string_literal: true
-
-require 'spec_helper'
-
-RSpec.describe Geo::Fdw::GeoNode, :geo, type: :model do
-  context 'relationships' do
-    it { is_expected.to have_many(:geo_node_namespace_links).class_name('Geo::Fdw::GeoNodeNamespaceLink') }
-  end
-end