pf: Fix interface counters for af-to rules

An inbound af-to rule creates a state bypassing outbound pf_test().
In such case increase counters of the outbound interface directly in
pf_route() for post-af-to address family.

For outbound af-to rules ensure that post-af-to address family is used
to increase interface counters.

Reviewed by: kp
Sponsored by: InnoGames GmbH
Differential Revision: https://reviews.freebsd.org/D52448