Move login_as after creating data for a test

It doesn't really affect the tests, but it helps isolate useless
assignments, and we already did it this way 94% of the time.

spec/features/admin/homepage/homepage_spec.rb

@@ -3,13 +3,13 @@ require "rails_helper"
 describe "Homepage" do
 
   before do
-    admin = create(:administrator).user
-    login_as(admin)
-
     Setting["homepage.widgets.feeds.proposals"] = false
     Setting["homepage.widgets.feeds.debates"] = false
     Setting["homepage.widgets.feeds.processes"] = false
     Setting["feature.user.recommendations"] = false
+
+    admin = create(:administrator).user
+    login_as(admin)
   end
 
   let!(:proposals_feed)    { create(:widget_feed, kind: "proposals") }