Render markdown snippets on Geo secondary sites

app/models/snippet_blob.rb

@@ -21,6 +21,10 @@ class SnippetBlob
     data.bytesize
   end
 
+  def commit_id
+    nil
+  end
+
   def data
     snippet.content
   end

changelogs/unreleased/jsl-snippet-fix.yml

+---
+title: Fix single file snippets display for Geo secondary sites
+merge_request: 46812
+author:
+type: fixed

qa/qa/specs/features/ee/browser_ui/geo/geo_replication_project_snippets_spec.rb

 # frozen_string_literal: true
 
 module QA
-  RSpec.describe 'Geo', :orchestrated, :geo, quarantine: { issue: 'https://gitlab.com/gitlab-org/gitlab/-/issues/262103', type: :bug } do
+  RSpec.describe 'Geo', :orchestrated, :geo do
     describe 'Project snippet' do
       let(:snippet_title) { "Geo project snippet-#{SecureRandom.hex(8)}" }
       let(:snippet_description) { 'Geo snippet description' }