test: mark test_cannot_run_js as flaky

This test has been failing occasionally since it was introduced ~5 days
ago. It was the most common failing JS test in the most recent
reliability report. Mark it as flaky.

Fixes: #48180
Refs: #47986
Refs: nodejs/reliability#576
PR-URL: #48181
Reviewed-By: Chengzhong Wu <legendecas@gmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

Author: kvakil

test/root.status

@@ -1,3 +1,6 @@
+[true]
+js-native-api/test_cannot_run_js/test: PASS,FLAKY
+
 [$mode==debug]
 async-hooks/test-callback-error: SLOW
 async-hooks/test-emit-init: SLOW