test: expanded assertions for console.timeEnd() output

Added assertions to verify that console.time() coerces labels to
strings correctly, by comparing against the expected output values of
console.timeEnd().

This helps resolve https://github.com/nodejs/node/issues/14544 but will
not address the whole thing.

PR-URL: https://github.com/nodejs/node/pull/17368
Refs: https://github.com/nodejs/node/pull/14643


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Sakthipriyan Vairamani <thechargingvolcano@gmail.com>