test: fix flaky test by removing timer

This fixes one of the tests that has been failing on CI on freebsd for
a bit by removing an unnecessary timer.

PR-URL: https://github.com/nodejs/node/pull/9199
Fixes: https://github.com/nodejs/node/issues/7929


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>