The password is not included in the backup. So you need to find the password somewhere else, or just make up a new one.
Anyway, to restore that backup, you first create the database, grant access to it, and then pipe the sql file into mysql. Something like this:
mysql -u root -proot
create database cacti;
grant all privileges on cacti.* to cacti@localhost identified by 'cactipassword';
mysql -u root -proot cacti <cacti-metadata-backup.sql
This assumes the root password is root. I suggest you change it to something else.