ikev2: Send deletes also for rekeyed SAs

ikev2: Send deletes also for rekeyed SAs

This way we can use the IKE_REKEYED state for both redundant and old SAs
to suppress ike_updown().

In the ike-delete task we don't suppress events in state IKE_REKEYING as
that's the case when we delete an SA the peer is currently rekeying with
multiple key exchanges.