[Rails5] fix Projects::VulnerabilityFeedbackController didn't match the schema

ee/changelogs/unreleased/rails5-fix-6747.yml

+---
+title: "[Rails5] fix Projects::VulnerabilityFeedbackController didn't match the schema"
+merge_request: 6320
+author: Jasper Maes
+type: fixed

ee/spec/controllers/projects/vulnerability_feedback_controller_spec.rb

@@ -160,8 +160,18 @@ describe Projects::VulnerabilityFeedbackController do
 
     def create_feedback(user:, project:, params:)
       sign_in(user)
+      post_params = {
+        namespace_id: project.namespace.to_param,
+        project_id: project,
+        vulnerability_feedback: params,
+        format: :json
+      }
 
-      post :create, namespace_id: project.namespace.to_param, project_id: project, vulnerability_feedback: params, format: :json
+      if Gitlab.rails5?
+        post :create, params: post_params, as: :json
+      else
+        post :create, post_params
+      end
     end
   end