test: fix addons/dlopen-ping-pong for npm 7.0.1

This partially reverts c87641aa as node-gyp no longer
puts shared objects in an inconsistent location.

PR-URL: https://github.com/nodejs/node/pull/35667


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Rod Vagg <rod@vagg.org>
Reviewed-By: Daijiro Wachi <daijiro.wachi@gmail.com>