test: log errors in test-fs-readfile-tostring-fail

The test writes out a large file via `fs.createWriteStream()` but was
not listening for the `error` event, which the `fs` docs describe as the
reliable way to detect write errors.

PR-URL: https://github.com/nodejs/node/pull/27058


Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>