resolvectl: fix JSON reply cleanup in varlink_dump_dns_configuration

resolvectl: fix JSON reply cleanup in varlink_dump_dns_configuration

varlink_call_and_log() does not hand out a new reference for the reply
object, so the caller should not unref it. The _cleanup_(sd_json_variant_unrefp)
on reply was therefore wrong from the start.

The original TAKE_PTR(reply) was working around this incorrect cleanup
by preventing it from firing, but that left reply's refcount one too
high after sd_json_variant_ref(v) incremented the parent's count.

Fix by dropping _cleanup_(sd_json_variant_unrefp) from the reply
variable declaration entirely, as suggested by Lennart Poettering.

Signed-off-by: dongshengyuan <dongshengyuan@uniontech.com>