Allow apps to be installed if local tiller

This means we can disregard whether Helm is installed or not

Move specs regarding set_initial_status to
cluster_application_initial_status.rb as not every application has the
common set_initial_status (elasticstack and jupyterhub)

app/models/clusters/concerns/application_core.rb

@@ -15,7 +15,7 @@ module Clusters
         def set_initial_status
           return unless not_installable?
 
-          self.status = status_states[:installable] if cluster&.application_helm_available?
+          self.status = status_states[:installable] if cluster&.application_helm_available? || Feature.enabled?(:managed_apps_local_tiller)
         end
 
         def can_uninstall?

spec/support/shared_examples/models/cluster_application_initial_status.rb

@@ -6,8 +6,30 @@ shared_examples 'cluster application initial status specs' do
 
     subject { described_class.new(cluster: cluster) }
 
+    context 'local tiller feature flag is disabled' do
+      before do
+        stub_feature_flags(managed_apps_local_tiller: false)
+      end
+
+      it 'sets a default status' do
+        expect(subject.status_name).to be(:not_installable)
+      end
+    end
+
+    context 'local tiller feature flag is enabled' do
+      before do
+        stub_feature_flags(managed_apps_local_tiller: true)
+      end
+
+      it 'sets a default status' do
+        expect(subject.status_name).to be(:installable)
+      end
+    end
+
     context 'when application helm is scheduled' do
       before do
+        stub_feature_flags(managed_apps_local_tiller: false)
+
         create(:clusters_applications_helm, :scheduled, cluster: cluster)
       end
 
@@ -16,7 +38,7 @@ shared_examples 'cluster application initial status specs' do
       end
     end
 
-    context 'when application is scheduled' do
+    context 'when application helm is installed' do
       before do
         create(:clusters_applications_helm, :installed, cluster: cluster)
       end

spec/support/shared_examples/models/cluster_application_status_shared_examples.rb

 # frozen_string_literal: true
 
 shared_examples 'cluster application status specs' do |application_name|
-  describe '#status' do
-    let(:cluster) { create(:cluster, :provided_by_gcp) }
-
-    subject { described_class.new(cluster: cluster) }
-
-    it 'sets a default status' do
-      expect(subject.status_name).to be(:not_installable)
-    end
-  end
-
   describe '#status_states' do
     let(:cluster) { create(:cluster, :provided_by_gcp) }