Merge branch 'right-sidebar-topbar-fix' into 'master'

Show top-bar full width when right-sidebar is present

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/140304



Merged-by: Justin Ho Tuan Duong <hduong@gitlab.com>
Approved-by: Julia Miocene <jmiocene@gitlab.com>
Approved-by: Justin Ho Tuan Duong <hduong@gitlab.com>
Approved-by: Denys Mishunov <dmishunov@gitlab.com>
Approved-by: Fernando Cardenas <14022659-fernando-c@users.noreply.gitlab.com>
Co-authored-by: Sascha Eggenberger <seggenberger@gitlab.com>