ArrowBuf copying from GetReadableBuffer causes slowness

### Describe the usage question you have. Please include as many useful details as possible.

I'm using Arrow Flight and discovered an extra copy action while testing performance impact.

` ReadableBuffer readableBuffer = fastPath ? getReadableBuffer(stream) : null;
if (readableBuffer != null) {
readableBuffer.readBytes(buf.nioBuffer(0, size));
} `

The flame graph shows that after enabling zero_copy, ArrowBuf copying from GetReadableBuffer causes slowness.
Why does this copy occur?
Or is it because arrowbuf needs to manage its own memory, so the ownership must be transferred from netty?

### Component(s)

FlightRPC

Comece pelo caminho rápido do FlightRPC mostrado na issue, acompanhando getReadableBuffer por ReadableBuffer.readBytes até o destino ArrowBuf e comparando com o flame graph relatado. Determine se a cópia é necessária para a propriedade ou o gerenciamento de memória e documente a causa ou uma forma claramente suportada de evitá-la.

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