Overflows in AverageIntervalRateLimiter's refill() and getWaitInterval()

It seems that there are more overflow in other places, and a concurrent issue.
I will post a patch within one or 2 days after I figure out adding new unittest cases.

Please see the following two lines. Once it overflows, it will cause wrong behavior. For unconfigured RateLimiters, we should have simpler logic to byPass the check.

https://github.com/apache/hbase/blob/master/hbase-server/src/main/java/org/apache/hadoop/hbase/quotas/AverageIntervalRateLimiter.java#L37

https://github.com/apache/hbase/blob/master/hbase-server/src/main/java/org/apache/hadoop/hbase/quotas/AverageIntervalRateLimiter.java#L51