test: plug AliasedBuffer cctest memory leak

No need to heap-allocate values here.

PR-URL: https://github.com/nodejs/node/pull/20665


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>