test: deflake test-net-throttle

Sometimes the test completes with only two data chunks received on the
client.

Fixes: #40507
PR-URL: #48599
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: Jacob Smith <jacob@frende.me>
Reviewed-By: LiviaMedeiros <livia@cirno.name>
Reviewed-By: Mohammed Keyvanzadeh <mohammadkeyvanzade94@gmail.com>
Reviewed-By: Darshan Sen <raisinten@gmail.com>
Reviewed-By: Nitzan Uziely <linkgoron@gmail.com>

test/parallel/test-net-throttle.js

@@ -84,5 +84,5 @@ server.listen(0, () => {
 
 process.on('exit', () => {
   assert.strictEqual(chars_recved, totalLength);
-  assert.strictEqual(npauses > 2, true);
+  assert.ok(npauses > 1, `${npauses} > 1`);
 });