Remove old tier badge code
Now that we're no longer using the old tier badge format (**(FREE SELF)**
), we should clean up all the old code that's no longer needed.
Some details are here: https://gitlab.com/gitlab-org/gitlab-docs/-/blob/main/doc/development.md?ref_type=heads#update-badges
But there are also pipeline jobs, I think. And work needed in all of the doc repos, as well as gitlab-doc.
There is no priority for this issue, but I wanted to capture that we need to do this work.
Edited by Suzanne Selhorn