The debug URL "/thread-group?all&json" returns metric keys as user_ns,
kernel_ns, and iowait_ns. However, the unit is second instead of
nanosecond. This fixes the misleading metric keys.
Tests:
- Add test in test_io_mgr_threads to verify the metric keys.
Change-Id: I15a8cf0a318bc7122d1f5df29f18d8e467249ef7
Reviewed-on: http://gerrit.cloudera.org:8080/20658
Reviewed-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>