Support for unlimited levels of compaction

### Problem

Currently we have `merkleDb.maxCompactionLevel` property to specify a maximal supported compaction level for the data files. However, eventually we may come to the conclusion that we don't need these levels at all. This ticket describes changed to be done to make it happen.

### Solution

1. Remove the property from `MerkleDbConfig`
2. Update `DataFileCompactor#compact`
3. Update `MerkleDbStatistics`

### Alternatives

_No response_

Locate MerkleDbConfig, DataFileCompactor#compact, and MerkleDbStatistics, then trace references to maxCompactionLevel and existing compaction behavior. Done means the configuration property is removed and the compactor and statistics support unlimited compaction levels consistently; check the affected tests if present.

Written by the indexing model from the issue text.