Policy DB script can only be used with a specific MariaDB version, which uses a mysql binary located under /usr/bin (https://git.onap.org/oom/tree/kubernetes/policy/resources/config/db.sh):

mysql() { /usr/bin/mysql  -h ${MYSQL_HOST} -P ${MYSQL_USER} "$@"; }; 

In the values.yaml the mariadb version is hardcoded, even, if the common template uses a newer version:

mariadb:
  image: mariadb:10.5.8 

Solution:

1. use the globally defined mariadb version
2. change the db script to use mysql without fixed path