Merge branch 'sh-fix-issue-336538' into 'master'

Update background migration to use main instead of master [RUN AS-IF-FOSS]

See merge request gitlab-org/gitlab!66492

lib/gitlab/background_migration/backfill_snippet_repositories.rb

@@ -105,7 +105,7 @@ module Gitlab
       end
 
       def commit_attrs
-        @commit_attrs ||= { branch_name: 'master', message: 'Initial commit' }
+        @commit_attrs ||= { branch_name: 'main', message: 'Initial commit' }
       end
 
       def create_commit(snippet)

spec/lib/gitlab/background_migration/backfill_snippet_repositories_spec.rb

@@ -304,7 +304,7 @@ RSpec.describe Gitlab::BackgroundMigration::BackfillSnippetRepositories, :migrat
   end
 
   def blob_at(snippet, path)
-    raw_repository(snippet).blob_at('master', path)
+    raw_repository(snippet).blob_at('main', path)
   end
 
   def repository_exists?(snippet)