IMPALA-4853: Skip test_kudu_dml_reporting if Kudu is not supported.
IMPALA-4853: Skip test_kudu_dml_reporting if Kudu is not supported.

This test is failing on distros that don't support Kudu, but it
shouldn't even be run.

Tested by setting KUDU_IS_SUPPORTED to false, and then trying to
run the test, confirming that it gets skipped. When the env var
KUDU_IS_SUPPORTED is true, the test runs.

Change-Id: Ia36319228d4e9cac9cb675f3207ef2ba39f24e7e
Reviewed-on: http://gerrit.cloudera.org:8080/5854
Reviewed-by: Michael Brown <97e4d5d0e400e5ad37382425ea95bde8b3933403@cloudera.com>
Reviewed-by: Matthew Jacobs <df2fa7c39d141dc5dc5589fed74180e757ed6c9a@cloudera.com>
Tested-by: Impala Public Jenkins

michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,michaelhkw/incubator-impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,cloudera/Impala,michaelhkw/incubator-impala