Remove inefficient saveListElementsBatch API

Remove inefficient saveListElementsBatch API

CpsDataService::saveListElementsBatch method is not needed as
saveListElements supports saving multiple list elements in a single
operation. This both simplifies implementation and greatly improves
performance when saving list elements, as the Yang parser need only
run once for the whole batch.

- Change InventoryPersistence to save CM-handles in batches of 100
  using existing CpsDataService::saveListElements method.
- Remove not needed CpsDataService::saveListElementBatch.

Issue-ID: CPS-2019
Signed-off-by: danielhanrahan <daniel.hanrahan@est.tech>
Change-Id: I8b74dda2917e094d064b42f2c0e4d57029b90395