Remove Geo::Fdw::Namespace model

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

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

@@ -10,7 +10,6 @@ module Geo
       serialize :selective_sync_shards, Array # rubocop:disable Cop/ActiveRecordSerialize
 
       has_many :geo_node_namespace_links, class_name: 'Geo::Fdw::GeoNodeNamespaceLink'
-      has_many :namespaces, class_name: 'Geo::Fdw::Namespace', through: :geo_node_namespace_links
     end
   end
 end

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

@@ -6,7 +6,6 @@ module Geo
       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
-      belongs_to :namespace, class_name: 'Geo::Fdw::Namespace', inverse_of: :geo_nodes
     end
   end
 end

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

-# frozen_string_literal: true
-
-module Geo
-  module Fdw
-    class Namespace < ::Geo::BaseFdw
-      include Routable
-
-      self.primary_key = :id
-      self.inheritance_column = nil
-      self.table_name = Gitlab::Geo::Fdw.foreign_table_name('namespaces')
-
-      has_many :geo_node_namespace_links, class_name: 'Geo::Fdw::GeoNodeNamespaceLink'
-      has_many :geo_nodes, class_name: 'Geo::Fdw::GeoNode', through: :geo_node_namespace_links
-      belongs_to :parent, class_name: "Namespace"
-    end
-  end
-end

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

@@ -5,6 +5,5 @@ 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) }
-    it { is_expected.to belong_to(:namespace).class_name('Geo::Fdw::Namespace').inverse_of(:geo_nodes) }
   end
 end

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

@@ -5,6 +5,5 @@ 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') }
-    it { is_expected.to have_many(:namespaces).class_name('Geo::Fdw::Namespace').through(:geo_node_namespace_links) }
   end
 end

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

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