Refactor rspec test suite to remove duplications

Also, one of the tests was dependent of the privous, but even with-
out running the previous it would pass, but it wouldn't be testing
what it should. Now this test is not dependent on the previous one,
and its assertion will always happen after filtering by milestone:
The test in question is 'closes when the search bar is unfocused'

spec/features/issues/filtered_search/dropdown_milestone_spec.rb

@@ -39,16 +39,28 @@ describe 'Dropdown milestone', :js do
   end
 
   describe 'behavior' do
-    it 'opens when the search bar has milestone:' do
-      filtered_search.set('milestone:')
+    context 'filters by "milestone:"' do
+      before do
+        filtered_search.set('milestone:')
+      end
 
-      expect(page).to have_css(js_dropdown_milestone, visible: true)
-    end
+      it 'opens when the search bar has milestone:' do
+        expect(page).to have_css(js_dropdown_milestone, visible: true)
+      end
 
-    it 'closes when the search bar is unfocused' do
-      find('body').click
+      it 'closes when the search bar is unfocused' do
+        find('body').click
 
-      expect(page).to have_css(js_dropdown_milestone, visible: false)
+        expect(page).to have_css(js_dropdown_milestone, visible: false)
+      end
+
+      it 'hides loading indicator when loaded' do
+        expect(find(js_dropdown_milestone)).not_to have_css('.filter-dropdown-loading')
+      end
+
+      it 'loads all the milestones when opened' do
+        expect(filter_dropdown).to have_selector('.filter-dropdown .filter-dropdown-item', count: 6)
+      end
     end
 
     it 'shows loading indicator when opened' do
@@ -58,18 +70,6 @@ describe 'Dropdown milestone', :js do
         expect(page).to have_css('#js-dropdown-milestone .filter-dropdown-loading', visible: true)
       end
     end
-
-    it 'hides loading indicator when loaded' do
-      filtered_search.set('milestone:')
-
-      expect(find(js_dropdown_milestone)).not_to have_css('.filter-dropdown-loading')
-    end
-
-    it 'loads all the milestones when opened' do
-      filtered_search.set('milestone:')
-
-      expect(filter_dropdown).to have_selector('.filter-dropdown .filter-dropdown-item', count: 6)
-    end
   end
 
   describe 'filtering' do