cache: position does not require full cache

cache: position does not require full cache

position refers to the rule handle, it has similar cache requirements as
replace rule command, relax cache requirements.

Commit e5382c0d08e3 ("src: Support intra-transaction rule references")
uses position.id for index support which requires a full cache, but
only in such case.

Fixes: 01e5c6f0ed03 ("src: add cache level flags")
Tested-by: Eric Garver <eric@garver.life>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>