Add a spec to ensure Crowd login form is shown even when sign-in is disabled

features/login_form.feature

 Feature: Login form
-  Scenario: I see crowd form
+  Scenario: I see Crowd form
     Given Crowd integration enabled
     When I visit sign in page
     Then I should see Crowd login form
+
+  Scenario: I see Crowd form when sign-in is disabled
+    Given Crowd integration enabled
+    And Sign-in is disabled
+    When I visit sign in page
+    Then I should see Crowd login form

features/steps/login_form.rb

@@ -5,18 +5,18 @@ class Spinach::Features::LoginForm < Spinach::FeatureSteps
   include SharedUser
   include SharedSearch
 
+  step 'Sign-in is disabled' do
+    allow_any_instance_of(ApplicationHelper).to receive(:signin_enabled?).and_return(false)
+  end
+
   step 'Crowd integration enabled' do
-    @providers_orig = Gitlab::OAuth::Provider.providers
-    @omniauth_conf_orig = Gitlab.config.omniauth.enabled
     expect(Gitlab::OAuth::Provider).to receive(:providers).and_return([:crowd])
-    allow_any_instance_of(ApplicationHelper).to receive(:user_omniauth_authorize_path).and_return(root_path)
     expect(Gitlab.config.omniauth).to receive(:enabled).and_return(true)
+    allow_any_instance_of(ApplicationHelper).to receive(:user_omniauth_authorize_path).and_return(root_path)
   end
 
   step 'I should see Crowd login form' do
     expect(page).to have_selector '#tab-crowd form'
-    Gitlab::OAuth::Provider.stub(:providers).and_return(@providers_orig)
-    Gitlab.config.omniauth.stub(:enabled).and_return(@omniauth_conf_orig)
   end
 
   step 'I visit sign in page' do