Add index to backups on user_id column (#25647)

db/migrate/20230630145300_add_index_backups_on_user_id.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+class AddIndexBackupsOnUserId < ActiveRecord::Migration[6.1]
+  disable_ddl_transaction!
+
+  def change
+    add_index :backups, :user_id, algorithm: :concurrently
+  end
+end