Merge branch '39653-hide-section_start-and-section_end-in-pipeline-emails' into 'master'
Resolve "Hide `section_start` and `section_end` in pipeline emails"
Closes #39653
See merge request gitlab-org/gitlab-ce!15534
(cherry picked from commit 3e558d8d)
4b4e83dc Add CSS hidden class in mailer layout