Add test for #8307.

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
fix for iptables cleanup 8307

Docker-DCO-1.1-Signed-off-by: Jessica Frazelle <jess@docker.com> (github: jfrazelle)
Merge pull request #8590 from jfrazelle/8307-iptables-d-restart-fix

On daemon shutdown iptables cleanup successfully