[JDK8] Replace AtomicLong with LongAdder

Currently we use many AtomicLong in HBase Region Code ，such as BucketCache calss realCacheSize,heapSize,blockNumber,accessCount and HRegion calss compactionNumBytesCompacted etc .

In JDK8 LongAdder is faster than AtomicLong ,should use this replace AtomicLong