test: fix test-performance-measure

Refs: nodejs/node#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 nodejs/node#42949 this
is likely what happened.

I have updated the assert.ok test to allow some variation in
the test.

PR-URL: nodejs/node#44637
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Akhil Marsonya <akhil.marsonya27@gmail.com>
Reviewed-By: Antoine du Hamel <duhamelantoine1995@gmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

test/parallel/test-performance-measure.js

@@ -5,11 +5,12 @@ const assert = require('assert');
 
 const { PerformanceObserver, performance } = require('perf_hooks');
 const DELAY = 1000;
+const ALLOWED_MARGIN = 10;
 
 const expected = ['Start to Now', 'A to Now', 'A to B'];
 const obs = new PerformanceObserver(common.mustCall((items) => {
   items.getEntries().forEach(({ name, duration }) => {
-    assert.ok(duration > DELAY);
+    assert.ok(duration > (DELAY - ALLOWED_MARGIN));
     assert.strictEqual(expected.shift(), name);
   });
 }));