numericPersistentMetrics should not be cleared for regions that are not being closed

when a region is closed, the region level dynamic metrics "numericPersistentMetrics" are cleared for all regions on the same region servers. It is OK for numericMetrics and timeVaryingMetrics. But not right for numericPersistentMetrics, because those value are accumulated and not be reset at poll time. To keep the right value, only the metrics for the closed region should be cleared, numericPersistentMetrics for other regions should be kept.