Clean status_reason on make_externally_ cluster apps transitions

Recently added artifact parsing added 2 new transitions. This MR adds
a status_reason cleanup for this transitions to prevent ambigious
states.

app/models/clusters/concerns/application_status.rb

@@ -79,7 +79,7 @@ module Clusters
             transition [:scheduled] => :uninstalling
           end
 
-          before_transition any => [:scheduled] do |application, _|
+          before_transition any => [:scheduled, :installed, :uninstalled] do |application, _|
             application.status_reason = nil
           end
 

spec/support/shared_examples/models/cluster_application_status_shared_examples.rb

@@ -262,6 +262,14 @@ RSpec.shared_examples 'cluster application status specs' do |application_name|
 
           expect(subject).to be_installed
         end
+
+        it 'clears #status_reason' do
+          expect(subject.status_reason).not_to be_nil
+
+          subject.make_externally_installed!
+
+          expect(subject.status_reason).to be_nil
+        end
       end
     end
 
@@ -292,6 +300,14 @@ RSpec.shared_examples 'cluster application status specs' do |application_name|
 
           expect(subject).to be_uninstalled
         end
+
+        it 'clears #status_reason' do
+          expect(subject.status_reason).not_to be_nil
+
+          subject.make_externally_uninstalled!
+
+          expect(subject.status_reason).to be_nil
+        end
       end
     end