Docker library (fix 20.04 EOL) + RHEL10

Adjust the triggers for Docker Library:

• 10.11 /10.6 are being triggered incorrectly.
• Add RHEL10 as base for MariaDB-12+
  Supported by https://github.com/MariaDB/mariadb-docker/pull/653

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BB PR: https://github.com/MariaDB/buildbot/pull/803