Fix deleting of feedback comment author

The comment author of a vulnerability feedback should be set to the
ghost user when the comment author is deleted.

ee/app/models/ee/user.rb

@@ -36,6 +36,7 @@ module EE
       has_many :assigned_epics,           foreign_key: :assignee_id, class_name: "Epic"
       has_many :path_locks,               dependent: :destroy # rubocop: disable Cop/ActiveRecordDependent
       has_many :vulnerability_feedback, foreign_key: :author_id, class_name: 'Vulnerabilities::Feedback'
+      has_many :commented_vulnerability_feedback, foreign_key: :comment_author_id, class_name: 'Vulnerabilities::Feedback'
 
       has_many :approvals,                dependent: :destroy # rubocop: disable Cop/ActiveRecordDependent
       has_many :approvers,                dependent: :destroy # rubocop: disable Cop/ActiveRecordDependent

ee/app/services/ee/users/migrate_to_ghost_user_service.rb

@@ -21,6 +21,7 @@ module EE
 
       def migrate_vulnerabilities_feedback
         user.vulnerability_feedback.update_all(author_id: ghost_user.id)
+        user.commented_vulnerability_feedback.update_all(comment_author_id: ghost_user.id)
       end
 
       def migrate_reviews

ee/spec/services/users/migrate_to_ghost_user_service_spec.rb

@@ -20,7 +20,7 @@ describe Users::MigrateToGhostUserService do
     end
   end
 
-  context 'vulnerability_feedback' do
+  context 'vulnerability_feedback author' do
     let!(:user)      { create(:user) }
     let(:service)    { described_class.new(user) }
 
@@ -29,6 +29,15 @@ describe Users::MigrateToGhostUserService do
     end
   end
 
+  context 'vulnerability_feedback comment author' do
+    let!(:user)      { create(:user) }
+    let(:service)    { described_class.new(user) }
+
+    include_examples "migrating a deleted user's associated records to the ghost user", Vulnerabilities::Feedback, [:comment_author] do
+      let(:created_record) { create(:vulnerability_feedback, comment_author: user) }
+    end
+  end
+
   context 'reviews' do
     let!(:user)      { create(:user) }
     let(:service)    { described_class.new(user) }