fix: Display proper conversation ID with click-to-open in SLA reports (#12570)

enterprise/app/views/api/v1/accounts/applied_slas/index.json.jbuilder

@@ -3,7 +3,7 @@ json.payload do
     json.applied_sla applied_sla.push_event_data
     json.conversation do
       conversation = applied_sla.conversation
-      json.id conversation.id
+      json.id conversation.display_id
       json.contact do
         json.name conversation.contact.name if conversation.contact
       end