ikev2: two CHILD SA connections, first should fail, but second should not hang

- an IKE SA with CHILD is established

- then the first CHILD_SA, with a bad proposal, is attemted

  Because the CHILD SA initiator state doesn't expect the NO PROPOSAL
  CHOSEN response it drops the packet:

"westnet-eastnet-ikev2-10" #5: dropping unexpected CREATE_CHILD_SA message containing NO_PROPOSAL_CHOSEN notification; message payloads: SK; encrypted payloads: N; missing payloads: SA,Ni,TSi,TSr

  The first CHILD_SA then starts retrying.  Presumably it deletes the
  state as the next attempt will create a new one?

"westnet-eastnet-ikev2-00" #3: IMPAIR: retransmit so timing out SA (may retry)
"westnet-eastnet-ikev2-00" #3: starting keying attempt 2 of an unlimited number, but releasing whack
"westnet-eastnet-ikev2-00" #3: deleting state (STATE_V2_CREATE_I)

- the second CHILD_SA is then initiated and crypto started

| adding Child Initiator KE and nonce ni work-order 4 for state #4

  but when the crypto comes back things seem confused and it gets
  re-suspended

| #4 wait sending, add to send next list using parent #1 unacknowledged 1 next message id=3 ike exchange window 1
| suspending state #4 and saving MD
| #4 is busy; has a suspended MD
| processing: [RE]START state #4 connection "westnet-eastnet-ikev2-10" 192.1.2.23 (in log_stf_suspend() at ikev2.c:2552)

Once this is fixed, ikev2-child-01-dh-pfs=no-downgrade=no and
ikev2-child-02-dh-pfs=yes-downgrade=yes should be updated to include
all cases (and this test deleted).