[MM-61515] Fix errcheck linter issues in webhook_test.go (#30684)

server/.golangci.yml

@@ -108,7 +108,6 @@ issues:
         channels/app/team.go|\
         channels/app/team_test.go|\
         channels/app/upload.go|\
-        channels/app/webhook_test.go|\
         channels/jobs/batch_worker_test.go|\
         channels/jobs/helper_test.go|\
         channels/jobs/hosted_purchase_screening/worker.go|\