BIT_PACKING is written by default when Definition or Repetition levels are empty

As discussed in https://github.com/apache/arrow/discussions/47113 , this package is writing the deprecated BIT_PACKING encoding to the column metadata and the DataPageHeader. This is only seems to happens when rep/def levels are empty. I think this is where it's happening:

```java
public class DevNullValuesWriter extends ValuesWriter {
....
public Encoding getEncoding() {
return BIT_PACKED;
}
}
```

Wouldn't it make sense to just return RLE?

I've seen this in parquet-java 1.15.1 and Overture Maps files using 1.13.1.

まず DevNullValuesWriter を見つけてその getEncoding() の実装を調べ、次にその値が列メタデータと DataPageHeader にどのように到達するかを追跡します。空の反復レベルと定義レベルによって、非推奨の BIT_PACKED エンコーディングが生成されず、代わりに RLE が使用されることを確認します。

索引モデルが issue の本文から書いたものです。