test: skip stringbytes-external-exceed-max on AIX

Add SKIP status for more tests in stringbytes-external-exceed-max that
are failing on AIX.

PR-URL: https://github.com/nodejs/node/pull/28516
Backport-PR-URL: https://github.com/nodejs/node/pull/29599


Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <michael_dawson@ca.ibm.com>