MB-15974 Clear out error in KVSender before retry
MB-15974 Clear out error in KVSender before retry

- The err needs to be set to nil before retry.
- MAX_KV_REQUEST_RETRY needs to be set to 0 for no retry. 1 means it will
retry once.
- Timekeeper is going to close the stopCh when aborting. Do not respond on stopCh.

Change-Id: I7f16aeef2db937ad697d67f25dfff19e81a717b9

jchris/indexing,jchris/indexing,jchris/indexing,jchris/indexing