Remove deprecated methods in RegionObserver

These deprecated methods are removed from RegionObserver: InternalScanner preFlushScannerOpen(ObserverContext, Store, List, InternalScanner) throws IOException; void preCompactSelection(ObserverContext, Store, List) throws IOException; void postCompactSelection(ObserverContext, Store, ImmutableList); InternalScanner preCompact(ObserverContext, Store, InternalScanner, ScanType) throws IOException; InternalScanner preCompactScannerOpen(ObserverContext, Store, List, ScanType, long, InternalScanner, CompactionRequest) throws IOException; InternalScanner preCompactScannerOpen( ObserverContext, Store store, List, ScanType, long, InternalScanner) throws IOException; void preSplit(ObserverContext) throws IOException; void preSplit(ObserverContext, byte[]) throws IOException; void postSplit(ObserverContext, Region, Region) throws IOException; void preSplitBeforePONR(ObserverContext, byte[], List) throws IOException; void preSplitAfterPONR(ObserverContext) throws IOException; void preRollBackSplit(ObserverContext) throws IOException; void postRollBackSplit(ObserverContext) throws IOException; void postCompleteSplit(ObserverContext) throws IOException; long preIncrementColumnValue(ObserverContext, byte[], byte[], byte[], long, boolean) throws IOException; long postIncrementColumnValue(ObserverContextc, byte[], byte[], byte[], long, boolean, long) throws IOException; KeyValueScanner preStoreScannerOpen(ObserverContext, Store, Scan, NavigableSet, KeyValueScanner) throws IOException; boolean postScannerFilterRow(ObserverContext, InternalScanner, byte[], int, short, boolean) throws IOException; boolean postBulkLoadHFile(ObserverContext, List, boolean) throws IOException; And this method is also removed since we never call it in our code base: InternalScanner preFlushScannerOpen(ObserverContext, Store, KeyValueScanner, InternalScanner, long) throws IOException; The deprecated annotation is removed for these two methods as they are still being used: void preFlush(ObserverContext) throws IOException; void postFlush(ObserverContextc) throws IOException;