[Bug] DBStorageCleanup always logs Deleted Indexes for entries as 0

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### Version

Pulsar (broker, bookie, zookeeper) -> 2.10.1
OS -> Ubuntu 18.04.6

### Minimal reproduce step

Publish some data for bookkeeper to trigger GCThread.

### What did you expect to see?

Number of entries which are deleted for number of ledgers

### What did you see instead?

I see number of entries as 0 always

### Anything else?

Here are the logs
05:15:10.184 [GarbageCollectorThread-11-1] INFO org.apache.bookkeeper.bookie.GarbageCollectorThread - Enter minor compaction, suspendMinor false
05:15:10.184 [GarbageCollectorThread-11-1] INFO org.apache.bookkeeper.bookie.GarbageCollectorThread - Do compaction to compact those files lower than 0.2
05:15:10.184 [GarbageCollectorThread-11-1] INFO org.apache.bookkeeper.bookie.GarbageCollectorThread - Compaction: entry log usage buckets[10% 20% 30% 40% 50% 60% 70% 80% 90% 100%] = [0, 0, 0, 0, 1, 12, 24, 22, 30, 268], compacted [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
05:16:09.802 [db-storage-cleanup-10-1] INFO org.apache.bookkeeper.bookie.storage.ldb.EntryLocationIndex - Deleting indexes for ledgers: [2486561, 2495075, 2495089, 2495070, 2495084, 2486362]
05:16:09.805 [db-storage-cleanup-10-1] INFO org.apache.bookkeeper.bookie.storage.ldb.EntryLocationIndex - Deleted indexes for 0 entries from 6 ledgers in 0.003 seconds

Looked into the code to troubleshoot and found that the field deletedIndex value is never updated in org.apache.bookkeeper.bookie.storage.ldb.EntryLocationIndex.removeOffsetFromDeletedLedgers()

### Are you willing to submit a PR?

- [X] I'm willing to submit a PR!

Start in org.apache.bookkeeper.bookie.storage.ldb.EntryLocationIndex, focusing on removeOffsetFromDeletedLedgers() and the deletedIndex field. Reproduce the DBStorageCleanup log with ledgers whose indexes are deleted, then verify the reported entry count is updated instead of remaining 0.

Written by the indexing model from the issue text.