rework eco container build

Currently amd64-rhel8-wordpress is an always fail.

This was fixed upstream. https://github.com/WordPress/wordpress-develop/commit/ea88e1fd71f40f9b96bd968e427e73492bddef57

There is a scheduler build on https://github.com/MariaDB/buildbot/blob/dev/.github/workflows/eco_containers.yml

Its triggered on the dev branch only, because this is the default buildbot branch I assume.

Is a better strategy to use the bbw_build_container_template.yml and make a dev version of the container running in the dev environment and move this to prod like the workers?