fix(ci): Use mysql_native_password on MySQL CI tests

[solracsf]

Summary

Tests print errors like:

"reqId":"Y3lZYyDY66erWDDo1YF5","level":3,"time":"2024-10-16T09:18:07+00:00","remoteAddr":"","user":"--","app":"mysql.setup","method":"","url":"--","message":"Database user creation failed.","userAgent":"--","version":"31.0.0.3","exception":{"Exception":"OC\\DB\\Exceptions\\DbalException","Message":"An exception occurred while executing a query: SQLSTATE[HY000]: General error: 1524 Plugin 'mysql_native_password' is not loaded","Code":1524,"Trace":[{"file":"/home/runner/actions-runner/_work/server/server/lib/private/DB/ConnectionAdapter.php","line":61,"function":"wrap","class":"OC\\DB\\Exceptions\\DbalException","type":"::","args":[{"__class__":"Doctrine\\DBAL\\Exception\\DriverException"}]},{"file":"/home/runner/actions-runner/_work/server/server/lib/private/Setup/MySQL.php","line":103,"function":"executeUpdate","class":"OC\\DB\\ConnectionAdapter","type":"->","args":["CREATE USER 'oc_admin'@'localhost' IDENTIFIED WITH mysql_native_password BY 'qn&?HhkmBYt3M&3h*76gL5GzaP?Cc4'"]},

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)