Merge branch '467686-consolidate-display-work-item-epic-issue-sidebar-to-new-flag' into 'master'

Update display_work_item_epic_issue_sidebar to work_item_epics

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/158613



Merged-by: Eugenia Grieff <egrieff@gitlab.com>
Approved-by: Rudy Crespo <rcrespo@gitlab.com>
Approved-by: Sam Word <sword@gitlab.com>
Approved-by: Eugenia Grieff <egrieff@gitlab.com>
Reviewed-by: Sam Word <sword@gitlab.com>
Co-authored-by: Rajan Mistry <rmistry@gitlab.com>