Contain all the things

This PR removes anchors where not necessary and instead ensures classes will be included with `contain` without an explicit dependency chain. These dependencies are generally not needed and should be only used if explicitly necessary, e.g. if a service depends on a database being present before start.

Furthermore, there are no more references to devstack in the code. :panda_face: 
I've updated the PR to remove support for `component::mysql::root_password`.