pf tests: ensure that we generate all permutations for SCTP multihome

The initial multihome implementation was a little simplistic, and failed
to create all of the required states. Given a client with IP 1 and 2 and
a server with IP 3 and 4 we end up creating states for 1 - 3 and 2 - 3,
as well as 3 - 1 and 4 - 1, but not for 2 - 4.

Check for this.

MFC after: 1 week
Sponsored by: Orange Business Services
Differential Revision: https://reviews.freebsd.org/D42362