[c++ client] temporary fix for KUDU-1688

KUDU-1688 Impala 'INSERT IGNORE' is slow due to VLOG(1) logging in
  client

Increased level for verbose log messages on per-row errors output by
batcher.

Change-Id: I61f039e94df130c225e0bb6a07f86200426c470a
Reviewed-on: http://gerrit.cloudera.org:8080/5067
Reviewed-by: Todd Lipcon <todd@apache.org>
Tested-by: Kudu Jenkins
Reviewed-on: http://gerrit.cloudera.org:8080/5072
1 file changed