pf: Fix table entry counter toggling

When updating a table, pf will keep existing table entry structures
corresponding to addresses that are in both of the old and new tables.
However, the update may also enable or disable per-entry counters which
are allocated separately. Thus when toggling PFR_TFLAG_COUNTERS, the
entries may be missing counters or may have unused counters allocated.

Fix the problem by modifying pfr_ina_commit() to transfer counters
from or to entries in the shadow table.

PR: 251414
Reported by: sigsys@gmail.com
Reviewed by: kp
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D27440