build: only try to find node when it's needed by the target

Right now `node -p process.versions.openssl` always gets run
in the Makefile even when it's not needed by the target
(e.g. `make clean`, `make test-only`). This patch makes it
a run time call instead of part of the global expansion.

PR-URL: https://github.com/nodejs/node/pull/24115


Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>