Use JavaScript in system tests by default

JavaScript is used by about 98% of web users, so by testing without it
enabled, we're only testing that the application works for a very
reduced number of users.

We proceeded this way in the past because CONSUL started using Rails 4.2
and truncating the database between JavaScript tests with database
cleaner, which made these tests terribly slow.

When we upgraded to Rails 5.1 and introduced system tests, we started
using database transactions in JavaScript tests, making these tests much
faster. So now we can use JavaScript tests everywhere without critically
slowing down our test suite.

spec/system/admin_spec.rb

@@ -42,7 +42,7 @@ describe "Admin" do
     expect(page).to have_content "You do not have permission to access this page"
   end
 
-  scenario "Access as SDG manager is not authorized", :js do
+  scenario "Access as SDG manager is not authorized" do
     create(:sdg_manager, user: user)
     login_as(user)
     visit admin_root_path
@@ -68,7 +68,7 @@ describe "Admin" do
     expect(page).not_to have_content "You do not have permission to access this page"
   end
 
-  scenario "Admin access links", :admin, :js do
+  scenario "Admin access links", :admin do
     Setting["feature.sdg"] = true
 
     visit root_path
@@ -81,7 +81,7 @@ describe "Admin" do
     expect(page).to have_link("SDG content")
   end
 
-  scenario "Admin dashboard", :admin, :js do
+  scenario "Admin dashboard", :admin do
     visit root_path
 
     click_link "Menu"
@@ -93,7 +93,7 @@ describe "Admin" do
     expect(page).not_to have_css("#valuation_menu")
   end
 
-  scenario "Admin menu does not hide active elements", :js, :admin do
+  scenario "Admin menu does not hide active elements", :admin do
     visit admin_budgets_path
 
     within("#admin_menu") do