test: add ancestor package.json checks for tmpdir

Policy tests can fail if a `package.json` exists in any of the parent
directories above the test. The existing checks are done for the
ancestors of the test directory but some tests execute from the tmpdir.

PR-URL: https://github.com/nodejs/node/pull/38285
Refs: https://github.com/nodejs/node/issues/38088
Refs: https://github.com/nodejs/node/issues/35600
Refs: https://github.com/nodejs/node/pull/35633


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