test: skip test due to file size limit

The test requires a file size limit that is greater than the string
size limit. Some aix machines might not meet this criteria so in
which case we should skip the test.

PR-URL: https://github.com/nodejs/node/pull/16273
Fixes: https://github.com/nodejs/node/issues/16319


Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: MichaëZasso <targos@protonmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Yuta Hiroto <hello@about-hiroppy.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>