Fix broken autocomplete controller spec

I think e73269a0 introduced the following spec failure:

  1) AutocompleteController project members GET #users with project ID should eq "jada.orn67"
     Failure/Error: it { expect(body.first["username"]).to eq user.username }
       
       expected: "jada.orn67"
            got: "steve_schaefer68"
       
       (compared using ==)
     # ./spec/controllers/autocomplete_controller_spec.rb:25:in `block (4 levels) in <top (required)>'

/cc @DouweM