Move group filter specs to JS (Karma)

Move group filter specs to JS (Karma)

• spec/features/dashboard/groups_list_spec.rb
• spec/features/explore/groups_list_spec.rb

The following discussion from gitlab-ce!19880 should be addressed:

• @rymai started a discussion:

  @MadLittleMods That looks good to me but I think this shows that we're testing at the wrong level here, I think the "resetting behavior" should be tested at the JS level because: i.e. when the filters are cleared, a XHR request is sent with no params. Currently, we're basically testing that loading the page (without any filters) vs filtering then defiltering shows the same results. Since in both cases we make an HTTP request, we could just test in JS that we're performing the correct HTTP request?

  Let's improve that later.