build: vcbuild uses default Python, not Py2

vcbuild now searches for the first python.exe found, and uses it, where
it used to look for Python 2 first.

PR-URL: https://github.com/nodejs/node/pull/30091


Reviewed-By: Christian Clauss <cclauss@me.com>
Reviewed-By: João Reis <reis@janeasystems.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>