[Bug] Core dumps are triggered by rocksdb compacting when shutdown the bookkeeper

**BUG REPORT**

***Describe the bug***

Core dumps are triggered rocksdb compacting when shutdown the bookkeeper process
```
[db-storage-cleanup-23-1:SingleDirectoryDbLedgerStorage@329] - Failed to trigger entry location index RocksDB compact
java.io.IOException: Error in RocksDB compact
at org.apache.bookkeeper.bookie.storage.ldb.KeyValueStorageRocksDB.compact(KeyValueStorageRocksDB.java:415)
at org.apache.bookkeeper.bookie.storage.ldb.EntryLocationIndex.compact(EntryLocationIndex.java:200)
at org.apache.bookkeeper.bookie.storage.ldb.SingleDirectoryDbLedgerStorage.lambda$entryLocationCompact$6(SingleDirectoryDbLedgerStorage.java:327)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:539)
at java.util.concurrent.FutureTask.run(FutureTask.java:264)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:304)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1136)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.lang.Thread.run(Thread.java:833)
Caused by: org.rocksdb.RocksDBException: Database shutdown
at org.rocksdb.RocksDB.compactRange(Native Method)
at org.rocksdb.RocksDB.compactRange(RocksDB.java:3344)
at org.rocksdb.RocksDB.compactRange(RocksDB.java:3319)
at org.apache.bookkeeper.bookie.storage.ldb.KeyValueStorageRocksDB.compact(KeyValueStorageRocksDB.java:407)
```

***To Reproduce***

Steps to reproduce the behavior:
1. Setting `entryLocationCompactionInterval` in bk_server.conf to enable `entryLocationCompaction`
2. Start the bookkeeper
3. Try to shutdown the bookkeeper when `GarbageCollectorThread` is running

***Expected behavior***

Bookkeeper process shutdown gracefully