Reduce array locking in LongArrayMultiStateCounter

Do this by checking if the data is all-zeros and returning
false in that case, without locking the java long array in JNI

Bug: 395954049
Test: atest PowerStatsTests; atest PowerStatsTests:BatteryUsageStatsProviderPerfTest#getBatteryUsageStats_accumulated
Flag: EXEMPT bugfix

Change-Id: I81639d9d571afcbb61ea047d8b2ab5e1b2bcf6f0