Improve message for upload request to LFS batch URL on secondary node

app/controllers/projects/lfs_api_controller.rb

 class Projects::LfsApiController < Projects::GitHttpClientController
+  include ApplicationSettingsHelper
+  include ApplicationHelper
+  include GitlabRoutingHelper
   include LfsRequest
 
   skip_before_action :lfs_check_access!, only: [:deprecated]
@@ -96,7 +99,7 @@ class Projects::LfsApiController < Projects::GitHttpClientController
     if upload_request? && Gitlab::Geo.secondary?
       render(
         json: {
-          message: 'You cannot do writing operations on a secondary GitLab Geo instance.'
+          message: "You cannot write to a secondary GitLab Geo instance. Please use #{geo_primary_default_url_to_repo(project)} instead."
         },
         content_type: "application/vnd.git-lfs+json",
         status: 403

spec/requests/lfs_http_spec.rb

@@ -861,6 +861,7 @@ describe 'Git LFS API and storage' do
   end
 
   describe 'when handling lfs batch request on a secondary Geo node' do
+    let!(:primary) { create(:geo_node, :primary) }
     let(:authorization) { authorize_user }
     let(:project) { create(:project) }
     let(:path) { "#{project.http_url_to_repo}/info/lfs/objects/batch" }
@@ -889,7 +890,7 @@ describe 'Git LFS API and storage' do
       post_lfs_json path, body.merge('operation' => 'upload'), headers
 
       expect(response).to have_http_status(403)
-      expect(json_response).to include('message' => 'You cannot do writing operations on a secondary GitLab Geo instance.')
+      expect(json_response).to include('message' => "You cannot write to a secondary GitLab Geo instance. Please use #{project.http_url_to_repo} instead.")
     end
   end