Move login items tests to the component

This way we reduce the number of system tests or, in some cases,
requests during system tests, making the tests faster.

We're still testing the interaction with the menu when users have the
right permissions.

spec/system/admin_spec.rb

@@ -68,19 +68,6 @@ describe "Admin" do
     expect(page).not_to have_content "You do not have permission to access this page"
   end
 
-  scenario "Admin access links", :admin do
-    Setting["feature.sdg"] = true
-
-    visit root_path
-    click_link "Menu"
-
-    expect(page).to have_link("Administration")
-    expect(page).to have_link("Moderation")
-    expect(page).to have_link("Valuation")
-    expect(page).to have_link("Management")
-    expect(page).to have_link("SDG content")
-  end
-
   scenario "Admin dashboard", :admin do
     visit root_path