Stub out aborting jobs in ansible launcher

The scheduler tests need to be able to abort jobs.  Even though
our Ansible launcher is not capable of aborting jobs yet, implement
the method so that we can override it in the RecordingLaunchServer
and exercise the scheduler.

Instead of using name+number to specify which build to abort, use
the UUID of the build.

Remove the build number entirely, since it isn't required.  In some
places it was used to determine whether the job had started.  In those
cases, use the build URL instead.

Also correct the launch server used in tests so that it does not send
two initial WORK_DATA packets.

Change-Id: I75525a2b48eb2761d599c039ba3084f09609dfbe
4 files changed