Test Reauthentication of CREATE_CHILD_SA IPsec SA sharing IKE SA.

West establishes 3 connections (1 IKE, with 3 Child SAs) to east.

Because west is configured with reauth=yes it triggers a full teardown
after 40s.

Since verything is +UP though it should all come back.

(it should also delay the teardown until after the new IKE SA is
online; later)
