test: fix test-performance-measure
Refs: https://github.com/nodejs/node/issues/42949
Looking at the documentation for setTimeout (https://nodejs.org/api/timers.html#settimeoutcallback-delay-args) there is no guarantee that setTimeout won't complete early.
From the failure of https://github.com/nodejs/node/issues/42949 this is likely what happened.
I have updated the assert.ok test to allow some variation in the test.