Explicitly disable JS in test deleting milestone

There's a usability issue in certain cases in browsers: when the
milestones table is at the bottom of the screen and it fills the screen
width completely, hovering over the link to delete a milestone makes the
"Delete milestone" tooltip cause a horizontal scrollbar. The scrollbar
makes it impossible for users to click the link.

We should probably fix this usuability issue; for now, I'm keeping the
test the way it was.

spec/shared/system/admin_milestoneable.rb

@@ -108,7 +108,7 @@ shared_examples "admin_milestoneable" do |factory_name, path_name|
     end
 
     context "Delete" do
-      scenario "Remove milestone" do
+      scenario "Remove milestone", :no_js do
         create(:milestone, milestoneable: milestoneable, title: "Title will it remove")
 
         visit path