Extract some basics to Geo::ApplicationController

Create Admin::Geo::ApplicationController that contains some base logic
for all Geo admin controllers (i.e. license check).

ee/app/controllers/admin/geo/application_controller.rb

+# frozen_string_literal: true
+
+class Admin::Geo::ApplicationController < Admin::ApplicationController
+  helper ::EE::GeoHelper
+
+  protected
+
+  def check_license!
+    unless Gitlab::Geo.license_allows?
+      flash[:alert] = _('You need a different license to use Geo replication.')
+      redirect_to admin_license_path
+    end
+  end
+end

ee/app/controllers/admin/geo/nodes_controller.rb

 # frozen_string_literal: true
 
-class Admin::Geo::NodesController < Admin::ApplicationController
-  before_action :check_license, except: :index
+class Admin::Geo::NodesController < Admin::Geo::ApplicationController
+  before_action :check_license!, except: :index
   before_action :load_node, only: [:edit, :update]
 
-  helper EE::GeoHelper
-
   # rubocop: disable CodeReuse/ActiveRecord
   def index
     @nodes = GeoNode.all.order(:id)
     @node = GeoNode.new
 
     unless Gitlab::Geo.license_allows?
-      flash.now[:alert] = _('You need a different license to enable Geo replication.')
+      flash.now[:alert] = _('You need a different license to use Geo replication.')
     end
 
     unless Gitlab::Database.postgresql_minimum_supported_version?
@@ -63,13 +61,6 @@ class Admin::Geo::NodesController < Admin::ApplicationController
     )
   end
 
-  def check_license
-    unless Gitlab::Geo.license_allows?
-      flash[:alert] = 'You need a different license to enable Geo replication'
-      redirect_to admin_license_path
-    end
-  end
-
   def load_node
     @node = GeoNode.find(params[:id])
   end

ee/app/controllers/admin/geo/projects_controller.rb

 # frozen_string_literal: true
 
-class Admin::Geo::ProjectsController < Admin::ApplicationController
-  before_action :check_license
+class Admin::Geo::ProjectsController < Admin::Geo::ApplicationController
+  before_action :check_license!
   before_action :load_registry, except: [:index]
   before_action :limited_actions_message!
 
-  helper ::EE::GeoHelper
-
   def index
     finder = ::Geo::ProjectRegistryStatusFinder.new
 
@@ -70,12 +68,6 @@ class Admin::Geo::ProjectsController < Admin::ApplicationController
 
   private
 
-  def check_license
-    unless Gitlab::Geo.license_allows?
-      redirect_to admin_license_path, alert: s_('Geo|You need a different license to use Geo replication')
-    end
-  end
-
   def load_registry
     @registry = ::Geo::ProjectRegistry.find_by_id(params[:id])
   end

ee/spec/controllers/admin/geo/nodes_controller_spec.rb

@@ -8,7 +8,7 @@ describe Admin::Geo::NodesController, :postgresql do
     end
 
     it 'displays a flash message' do
-      expect(controller).to set_flash[:alert].to('You need a different license to enable Geo replication')
+      expect(controller).to set_flash[:alert].to('You need a different license to use Geo replication.')
     end
   end
 
@@ -55,7 +55,7 @@ describe Admin::Geo::NodesController, :postgresql do
         allow(Gitlab::Geo).to receive(:license_allows?).and_return(false)
       end
 
-      it_behaves_like 'with flash message', :alert, 'You need a different license to enable Geo replication'
+      it_behaves_like 'with flash message', :alert, 'You need a different license to use Geo replication'
 
       it 'does not redirects to the license page' do
         go