tests: sys.netpfil.pf.forward.v6 fails in CI

sys.netpfil.pf.forward.v6 has been failing in CI. File a bug and disable
until it can be resolved.

PR:		260460
Sponsored by:	Netflix

tests/sys/netpfil/pf/forward.sh

@@ -102,6 +102,10 @@ v6_body()
 {
 	pft_init
 
+	if [ "$(atf_config_get ci false)" = "true" ]; then
+		atf_skip "https://bugs.freebsd.org/260460"
+	fi
+
 	epair_send=$(vnet_mkepair)
 	epair_recv=$(vnet_mkepair)