Follow-up: Fix sidebar epics count inconsitency

https://gitlab.com/gitlab-org/security/gitlab/-/merge_requests/1635 fixed displaying unauthorized epics from different group hierarchy on epics list, however, epics count on sidebar now shows inconsistent numbers because it does not use same filters in the count query.

For more information check https://gitlab.com/gitlab-org/security/gitlab/-/merge_requests/1635#note_677024534