Merge branch '434197-dashboard-sidebar-sizing' into 'master'

K8s dashboard UX improvements

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/140375



Merged-by: Coung Ngo <cngo@gitlab.com>
Approved-by: Emily Bauman <ebauman@gitlab.com>
Approved-by: Lorenz van Herwaarden <lvanherwaarden@gitlab.com>
Approved-by: Coung Ngo <cngo@gitlab.com>
Co-authored-by: Anna Vovchenko <avovchenko@gitlab.com>