src: simplify `TimerFunctionCall()` in `node_perf.cc`

Picking a path according to a boolean is essentially free,
compared to the cost of a function call. Also, remove an
unnecessary `TryCatch`.

PR-URL: https://github.com/nodejs/node/pull/23782


Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Matheus Marchini <mat@mmarchini.me>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>