IMPALA-3887: Wait for HDFS replication in data loading
IMPALA-3887: Wait for HDFS replication in data loading

When the data loading finishes, it is possible for some HDFS blocks to
be under replicated. If impala gets the metadata before the replication
is done, some tests may fail. This patch adds a replication waiting step
in the data loading script.

Change-Id: I88dfb7165b7515b3e96111436be490f2068ec322
Reviewed-on: http://gerrit.cloudera.org:8080/8846
Reviewed-by: Alex Behm <fe1626037acfc2dc542d2aa723a6d14f2464a20c@cloudera.com>
Tested-by: Impala Public Jenkins

cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala