Followup: Minor refactor to entity_leave_service.rb
Adding some small followup refactors from https://gitlab.com/gitlab-org/security/gitlab/-/merge_requests/900
- consider using scopes, https://gitlab.com/gitlab-org/security/gitlab/-/merge_requests/900#note_420124194
- refactor shared example to not use constant, https://gitlab.com/gitlab-org/security/gitlab/-/merge_requests/900#note_419201717
- remove extraneous values in parameterized comment, https://gitlab.com/gitlab-org/security/gitlab/-/merge_requests/900#note_419201716
Edited by Brett Walker