Change errors.Cause to errors.Is, because github.com/cockroachdb/errors
New() function create a error with error stack with depth 1, but
github.com/pkg/errors's New() function create error with no depth.
Signed-off-by: Xun Jiang <xun.jiang@broadcom.com>
Enlarge throttle of UT case TestThrottle_ShouldOutput to avoid occasional CI
failure due to timeout caused by test environment's CPU speed
Signed-off-by: Xun Jiang <jxun@vmware.com>