ClientModel: Use `clearArray` when returning array pool arrays for response buffering

See: https://github.com/Azure/azure-sdk-for-net/pull/41016#discussion_r1443336453

We would want to change this in both:
- ClientModel's StreamExtensions
- Azure.Core's [AzureBaseBuffersExtensions](https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/core/Azure.Core/src/Internal/AzureBaseBuffersExtensions.cs#L14)

@christothes FYI