Support Salt batch sizing for most important pipelines

Add parameter BATCH_SIZE to support Batch sizing for Salt to be
applied on huge amount of nodes.

Change-Id: If79b71f59a9758ebb6f46862a2d4a089696765c1
Related: PROD-27850 (PROD:27850)
Related: PROD-32646 (PROD:32646)
3 files changed