Temporarily skip flakey test case sys.netinet.fibs_test.udp_dontroute6 in CI

PR:		244172
Sponsored by:	The FreeBSD Foundation

tests/sys/netinet/fibs_test.sh

@@ -626,6 +626,9 @@ udp_dontroute_head()
 
 udp_dontroute_body()
 {
+	if [ "$(atf_config_get ci false)" = "true" ]; then
+		atf_skip "https://bugs.freebsd.org/244172"
+	fi
 	# Configure the TAP interface to use an RFC5737 nonrouteable address
 	# and a non-default fib
 	ADDR0="192.0.2.2"