test: fix tool path in test-doctool-versions.js

Path to the versions tool tested by test-doctool-versions.js would
be incorrect if the test temporary directory was redirected (e.g.
via NODE_TEST_DIR) outside of `test/`.

Signed-off-by: Richard Lau <riclau@uk.ibm.com>

PR-URL: https://github.com/nodejs/node/pull/32645
Refs: https://github.com/nodejs/node/pull/32518


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>