Reduce polling interval in feature spec

Rather than waiting 10 seconds which is an eternity for a computer, we
change the polling interval to something much lower. This vastly
improves our spec runtime

spec/features/clusters/installing_applications_shared_examples.rb

@@ -2,6 +2,9 @@
 
 RSpec.shared_examples "installing applications for a cluster" do |managed_apps_local_tiller|
   before do
+    # Reduce interval from 10 seconds which is too long for an automated test
+    stub_const("#{Clusters::ClustersController}::STATUS_POLLING_INTERVAL", 500)
+
     stub_feature_flags(managed_apps_local_tiller: managed_apps_local_tiller)
 
     visit cluster_path