src: remove unused perf_hooks uv handles

A couple of unused uv handles were accidentally left
in env.

PR-URL: https://github.com/nodejs/node/pull/15368


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Brian White <mscdex@mscdex.net>