Save infra resources

Save infra resources

- Only stable AR builds triggers dist test job. Today both stable
and not stable trigger distribution test.

- Jenkins queue has max 1 dist test job triggered by AR. This is
achieved by passing the same parameter BUNDLE_URL=autorelease to
the distribution test job, see: https://stackoverflow.com/questions/
8974170/jenkins-parameterized-job-that-only-queues-one-build

How this works:

Stable AR will trigger a dist test job with BUNDLE_URL=autorelease,
dist test job will resolve autorelease into last stable AR dist URL
and will pass this value down to the CSIT jobs.

Change-Id: I2bc42f1f2053997d2c364384accc0e68a53d4614
Signed-off-by: Luis Gomez <ecelgp@gmail.com>