pf: Do not short-circuit processing for REPLY_TO

When we find a state for packets that was created by a reply-to rule we
still need to process the packet. The state may require us to modify the
packet (e.g. in rdr or nat cases), which we won't do with the shortcut.

MFC after: 2 week
Sponsored by: Rubicon Communications, LLC ("Netgate")

(cherry picked from commit 6d786845cf63c8bf57174e3e43b0b5c5eca75be3)