[Flight client] Allow disabling the creation of a child allocator

### Describe the enhancement requested

`FlightClient` [always creates a child allocator](https://github.com/apache/arrow-java/blob/7cbf15994ae7c82fbcb178dded6b3f128219d9ad/flight/flight-core/src/main/java/org/apache/arrow/flight/FlightClient.java#L86). While this is good in the general case to track memory leaks, this prevents usage scenarios where vectors live longer than the Flight client.

What about adding a `FlightClient.Builder#createChildAllocator(boolean)` that would allow users to choose whether they want a child allocator (current behavior which will be the default) or directly use the provided one?

I can create a PR for this.

Comienza en flight/flight-core/src/main/java/org/apache/arrow/flight/FlightClient.java, alrededor de la línea 86, y sigue FlightClient.Builder. Verifica que, de forma predeterminada, se siga creando un allocator hijo, mientras que la nueva opción pueda usar directamente el allocator proporcionado. Se considera terminado cuando ambos modos de allocator estén cubiertos por las pruebas relevantes del cliente Flight.

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