Drop boilerplate comments

db/migrate/20210513093418_add_draft_column_to_merge_requests.rb

@@ -3,19 +3,6 @@
 class AddDraftColumnToMergeRequests < ActiveRecord::Migration[6.0]
   include Gitlab::Database::MigrationHelpers
 
-  # When using the methods "add_concurrent_index" or "remove_concurrent_index"
-  # you must disable the use of transactions
-  # as these methods can not run in an existing transaction.
-  # When using "add_concurrent_index" or "remove_concurrent_index" methods make sure
-  # that either of them is the _only_ method called in the migration,
-  # any other changes should go in a separate migration.
-  # This ensures that upon failure _only_ the index creation or removing fails
-  # and can be retried or reverted easily.
-  #
-  # To disable transactions uncomment the following line and remove these
-  # comments:
-  # disable_ddl_transaction!
-
   def up
     with_lock_retries do
       add_column :merge_requests, :draft, :boolean, default: false, null: false