errors: refactor `invalidArgType()`

`invalidArgType()` uses `includes()` in two places where `startsWith()`
and `endsWith()` are more appropriate (at least in my opinion). Switch
to those more specific functions.

PR-URL: https://github.com/nodejs/node/pull/15544


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>