add slow_requests! to filtered search tests which expect to see a loading spinner

spec/features/issues/filtered_search/dropdown_assignee_spec.rb

@@ -43,9 +43,11 @@ describe 'Dropdown assignee', :js do
     end
 
     it 'should show loading indicator when opened' do
+      Gitlab::Testing::RequestBlockerMiddleware.slow_requests!
       filtered_search.set('assignee:')
 
       expect(page).to have_css('#js-dropdown-assignee .filter-dropdown-loading', visible: true)
+      Gitlab::Testing::RequestBlockerMiddleware.allow_requests!
     end
 
     it 'should hide loading indicator when loaded' do

spec/features/issues/filtered_search/dropdown_author_spec.rb

@@ -51,9 +51,11 @@ describe 'Dropdown author', :js do
     end
 
     it 'should show loading indicator when opened' do
+      Gitlab::Testing::RequestBlockerMiddleware.slow_requests!
       filtered_search.set('author:')
 
       expect(page).to have_css('#js-dropdown-author .filter-dropdown-loading', visible: true)
+      Gitlab::Testing::RequestBlockerMiddleware.allow_requests!
     end
 
     it 'should hide loading indicator when loaded' do

spec/features/issues/filtered_search/dropdown_emoji_spec.rb

@@ -70,9 +70,11 @@ describe 'Dropdown emoji', :js do
       end
 
       it 'should show loading indicator when opened' do
+        Gitlab::Testing::RequestBlockerMiddleware.slow_requests!
         filtered_search.set('my-reaction:')
 
         expect(page).to have_css('#js-dropdown-my-reaction .filter-dropdown-loading', visible: true)
+        Gitlab::Testing::RequestBlockerMiddleware.allow_requests!
       end
 
       it 'should hide loading indicator when loaded' do

spec/features/issues/filtered_search/dropdown_label_spec.rb

@@ -66,10 +66,12 @@ describe 'Dropdown label', :js do
     end
 
     it 'shows loading indicator when opened and hides it when loaded' do
+      Gitlab::Testing::RequestBlockerMiddleware.slow_requests!
       filtered_search.set('label:')
 
       expect(page).to have_css("#{js_dropdown_label} .filter-dropdown-loading", visible: true)
       expect(find(js_dropdown_label)).not_to have_css('.filter-dropdown-loading')
+      Gitlab::Testing::RequestBlockerMiddleware.allow_requests!
     end
 
     it 'loads all the labels when opened' do

spec/features/issues/filtered_search/dropdown_milestone_spec.rb

@@ -50,9 +50,11 @@ describe 'Dropdown milestone', :js do
     end
 
     it 'should show loading indicator when opened' do
+      Gitlab::Testing::RequestBlockerMiddleware.slow_requests!
       filtered_search.set('milestone:')
 
       expect(page).to have_css('#js-dropdown-milestone .filter-dropdown-loading', visible: true)
+      Gitlab::Testing::RequestBlockerMiddleware.allow_requests!
     end
 
     it 'should hide loading indicator when loaded' do