assert: fix rejects stack trace and operator

This makes sure the stack trace is not removed due to a wrong stack
start function being used. It also fixes the wrong operator caused
by the same reason. This only applies in case an validation object
was used to validate the rejection passed to `assert.reject()` as
first argument.

PR-URL: https://github.com/nodejs/node/pull/27047


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>