test: fix flaky http timeout test

There is no guarantee that a timeout won't be delayed considerably due
to unrelated activity on the host. Instead of checking that the timeout
happens within a certain tolerance, simply check that it did not happen
too soon.

Fixes: #22041

PR-URL: #22403
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

test/sequential/test-http-client-timeout-option-with-agent.js

@@ -42,8 +42,9 @@ function doRequest() {
     timeout_events += 1;
     const duration = Date.now() - start;
     // The timeout event cannot be precisely timed. It will delay
-    // some number of milliseconds, so test it in second units.
-    assert.strictEqual(duration / 1000 | 0, HTTP_CLIENT_TIMEOUT / 1000);
+    // some number of milliseconds.
+    assert.ok(duration >= HTTP_CLIENT_TIMEOUT,
+              `${duration} < ${HTTP_CLIENT_TIMEOUT}`);
   }));
   req.end();