Replace MySQL dependency with MariaDB

[rossigee]

Summary

• Replace deprecated bitnami/mysql chart with bitnami/mariadb (drop-in MySQL replacement)
• Bitnami MySQL images are no longer available on Docker Hub (now commercial only)
• Update chart version to 1.10.0

Changes

• Replace mysql subchart with mariadb (version 18.1.6)
• Update values keys from mysql.* to mariadb.*
• Update templates to use mariadb.enabled and -mariadb service name
• MariaDB uses same MySQL JDBC driver, so Traccar configuration remains compatible

[tananaev]

What's going on here?

[rossigee]

I was having a stab at trying to fix the broken CI test I discovered while checking up on my other PR which has been long outstanding. But it was a waste of time, and I don't even use the chart any more, so I'll leave it and let someone else deal with it.