Use cluster endpoint at startup

[piceri]

This change allows deployment tracker to use the cluster endpoint at startup to send the current state of the cluster. This will reduce the load cause at startup when deployment tracker sends the state of the cluster one container at a time.

Change details:

• While the informers sync, events are no longer added to the work queue
• Once the informers have synced, use the pod informer to get the current list of running pods
• Any new events are then added the the work queue
• Current pod list is processed and deduped by deployment name + digest
• Send the list to the cluster endpoint
  • If this fails, deployment tracker does not continue to run
• Use the response to fill observed and unknown caches