test: mark test-vm-timeout-escape-nexttick flaky

This is a known failure so mark it such, so that
CI is green / amber while the issue is being progressed.

PR-URL: https://github.com/nodejs/node/pull/24712
Refs: https://github.com/nodejs/node/pull/24620
Refs: https://github.com/nodejs/node/issues/24120


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>