test: mark stringbytes-external-exceed-max tests as flaky on AIX

test: mark stringbytes-external-exceed-max tests as flaky on AIX · nodejs/node@2a57268

Original file line number	Diff line number	Diff line change
`@@ -20,3 +20,13 @@ openssl-providers/test-no-legacy-provider-option: SKIP`
`20`	`20`	`zlib-binding/test: SKIP`
`21`	`21`	`# https://github.com/nodejs/node/issues/34410`
`22`	`22`	`register-signal-handler/test: PASS,FLAKY`
	`23`	`+`
	`24`	`+[$system==aix]`
	`25`	`+# https://github.com/nodejs/node/issues/60494`
	`26`	`+stringbytes-external-exceed-max/test-stringbytes-external-exceed-max: PASS,FLAKY`
	`27`	`+stringbytes-external-exceed-max/test-stringbytes-external-exceed-max-by-1-hex: PASS,FLAKY`
	`28`	`+stringbytes-external-exceed-max/test-stringbytes-external-exceed-max-by-1-utf8: PASS,FLAKY`
	`29`	`+stringbytes-external-exceed-max/test-stringbytes-external-exceed-max-by-1-base64: PASS,FLAKY`
	`30`	`+stringbytes-external-exceed-max/test-stringbytes-external-exceed-max-by-2: PASS,FLAKY`
	`31`	`+stringbytes-external-exceed-max/test-stringbytes-external-exceed-max-by-1-ascii: PASS,FLAKY`
	`32`	`+stringbytes-external-exceed-max/test-stringbytes-external-exceed-max-by-1-binary: PASS,FLAKY`