This variable was used in two places:

1. `top_bar`, if the super sidebar is disabled. As it is now always
   enabled, this usage is obsolete.
2. `auto_devops_callout`. This is used via
   `app/views/projects/_flash_messages.html.haml` which is only included
   on the Project overview and Project empty page.

The variable was only set in the pages: Group Epics, Group Roadmap and
Issue/Epic Boards. All of these have no overlap with the
`auto_devops_callout` and therefore are safe to remove.