Update debian from buster to bullseye in www-gitlab-com

What does this MR do and why?

Updates debian base from buster to bullseye in :www-gitlab-com-ruby-3.0-node-16.

Replaces pip-install'd yamllint 1.25.0 with deb-packaged 1.26.0-2. Note that the latest version of yamllint is 1.27.1 as of writing.

Updates !294 (merged) !300 (merged) !356 (merged)