adding MariaDB 11 Melange Config

[johnfosborneiii]

• "mariadb-11: new image stream (latest non-tls release)"
  https://endoflife.date/mariadb

For new package PRs only

• This PR is marked as fixing a pre-existing package request bug
  • Alternatively, the PR is marked as related to a pre-existing package request bug, such as a dependency
• REQUIRED - The package is available under an OSI-approved or FSF-approved license
• REQUIRED - The version of the package is still receiving security updates
• This PR links to the upstream project's support policy (e.g. endoflife.date)

For new version streams

• The upstream project actually supports multiple concurrent versions.
• Any subpackages include the version string in their package name (e.g. name: ${{package.name}}-compat)
• The package (and subpackages) provides: logical unversioned forms of the package (e.g. nodejs, nodejs-lts)