Rewrite `ParquetRecordBatchStream` (async API) in terms of the PushDecoder

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

• part of [Epic] Parquet Reader Improvement Plan / Proposal - July 2025 #8000

We added the ParquetPushDecoder in #7997

One of the rationales is to avoid duplicating the control logic between the Async Reader and the Sync Reader.

However, it actually (temporarily) makes the problem worse by adding a 3rd copy of the control logic ala the xkcd standards effect

Describe the solution you'd like

1. Refactor the ParquetRecordBatchStream to use ParquetPushDecoder

Describe alternatives you've considered

Additional context

• Rewrite ParquetRecordBatchReader (sync api) in terms of the PushDecoder #8678 covers the sync API