In some places this file referred to the database in three different ways: database, DB and db. The last one caused confusion with the db namespace and the db folder. This commit removes this ambiguity by using the whole word 'database' everywhere
In Rails engine, migration files are in under `db/migrate` of engine.
Therefore, when rake task is executed in engine, `db/migrate` is
automatically added to `DatabaseTasks.migrations_paths`.
a18cf23a9c/activerecord/lib/active_record/railtie.rb (L39..L43)
However, if execute the rake task under dummy app, migration files will not
be loaded because engine's migration path setting process is not called.
Therefore, in order to load migration files correctly, it is necessary to
execute rake task under engine.
Fixes#30765
Occasionally we update the file generated by engine.
Therefore, I think that there is a task for updating as well as
application in the engine, it is convenient for updating.
