Remove setting version on :updating for prometheus

As we are now setting version on :updated for all applications now.

ee/app/models/ee/clusters/applications/prometheus.rb

@@ -16,7 +16,7 @@ module EE
 
           state_machine :status do
             after_transition any => :updating do |application|
-              application.update(last_update_started_at: Time.now, version: application.class.const_get(:VERSION))
+              application.update(last_update_started_at: Time.now)
             end
           end
         end

ee/spec/models/ee/clusters/applications/prometheus_spec.rb

@@ -14,16 +14,6 @@ describe Clusters::Applications::Prometheus do
         expect { subject.make_updating }.to change { subject.reload.last_update_started_at }.to be_within(1.second).of(Time.now)
       end
     end
-
-    context 'application install previously errored with older version' do
-      subject { create(:clusters_applications_prometheus, :installed, cluster: cluster, version: '6.7.2') }
-
-      it 'updates the application version' do
-        subject.make_updating
-
-        expect(subject.reload.version).to eq('6.7.3')
-      end
-    end
   end
 
   context '#updated_since?' do