Merge branch '419525-quick-action-to-add-0-estimate-does-not-work-as-expected-2' into 'master'

Support removing time estimate with /estimate 0

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/127721



Merged-by: Roy Zwambag <rzwambag@gitlab.com>
Approved-by: Roy Zwambag <rzwambag@gitlab.com>
Approved-by: Aaron Huntsman <ahuntsman@gitlab.com>
Reviewed-by: Missy Davies <ms.melissadavies@gmail.com>
Reviewed-by: Roy Zwambag <rzwambag@gitlab.com>
Co-authored-by: Ash McKenzie <amckenzie@gitlab.com>