Send compute.instance.create.end after launched_at is set

Downstream consumers of notifications want to know when an instance was
launched from the compute.instance.create.end notification.  This value
was previously set in the notification but commit
70196c4854e6cc1cb566dc9fc5b1a3397a4b69ab changed things so that it was
no longer set.  It will now be set, and is tested to be set.

Change-Id: If5ac00529d52e3898cda7fd942535ed3ba2039d5
Closes-bug: 1338736
Merge "Send compute.instance.create.end after launched_at is set"