Do not update feedback when it is persisted

Previously, we were trying to update the feedback records associated
with the vulnerabilities while dismissing them. This was causing long
update queries as one feedback can be associated with more than one
vulnerabilities while the users were trying to dismiss all those
vulnerability records.

Changelog: fixed
EE: true

ee/app/services/vulnerability_feedback/create_service.rb

@@ -134,7 +134,9 @@ module VulnerabilityFeedback
                                               dismiss_findings: false).execute
         end
 
-        raise ActiveRecord::Rollback unless vulnerability_feedback.save
+        unless vulnerability_feedback.persisted?
+          raise ActiveRecord::Rollback unless vulnerability_feedback.save
+        end
       end
     end
 

ee/spec/services/vulnerability_feedback/create_service_spec.rb

@@ -146,6 +146,19 @@ RSpec.describe VulnerabilityFeedback::CreateService, '#execute' do
           end
         end
       end
+
+      context 'when we already have persisted feedback' do
+        let!(:feedback) do
+          create(:vulnerability_feedback, :dismissal,
+                 project: project,
+                 pipeline: pipeline,
+                 project_fingerprint: project_fingerprint)
+        end
+
+        it 'does not update the feedback' do
+          expect { result }.not_to change { feedback.reload.updated_at }
+        end
+      end
     end
 
     context 'when feedback_type is issue' do