[kudu-tool-test] deflake ToolTestCopyTableParameterized.TestCopyTable
[kudu-tool-test] deflake ToolTestCopyTableParameterized.TestCopyTable

Under mode UPSERT_TO_EXIST_TABLE, destination table is not empty before
copying, it may has more rows than source table, so it may still has
more rows than source table after copying.

Change-Id: I089bdd5e737f4eef94068303516ceb0d5ddd3abb
Reviewed-on: http://gerrit.cloudera.org:8080/12932
Tested-by: Kudu Jenkins
Reviewed-by: Adar Dembo <866ca730bfc7f544e3ebce604ceeba4879f23df0@cloudera.com>

InspurUSA/kudu,helifu/kudu,InspurUSA/kudu,InspurUSA/kudu,helifu/kudu,helifu/kudu,InspurUSA/kudu,helifu/kudu,helifu/kudu,InspurUSA/kudu,InspurUSA/kudu,helifu/kudu,helifu/kudu,helifu/kudu,helifu/kudu,InspurUSA/kudu,InspurUSA/kudu,InspurUSA/kudu