test: mark test-fs-stat-bigint flaky on FreeBSD

Refs: nodejs#31727

PR-URL: nodejs#31728
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Denys Otrishko <shishugi@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/parallel/parallel.status

@@ -42,6 +42,8 @@ test-crypto-keygen: SKIP
 [$system==solaris] # Also applies to SmartOS
 
 [$system==freebsd]
+# https://github.com/nodejs/node/issues/31727
+test-fs-stat-bigint: PASS,FLAKY
 
 [$system==aix]