Merge branch '411420-unsubscribe-from-design-notification-emails' into 'master'

Add ability to unsubscribe from design management notifications

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/144247



Merged-by: Kassio Borges <kborges@gitlab.com>
Approved-by: Hinam Mehra <hmehra@gitlab.com>
Approved-by: Kassio Borges <kborges@gitlab.com>
Co-authored-by: Joseph Wambua <jjoshua@gitlab.com>