FileBufferingReadStream CopyToAsync Performance problem when wrapped

### Is there an existing issue for this?

- [X] I have searched the existing issues

### Describe the bug

Previously reported #24032 and fixed in #24609.

When buffering a response using a wrapper around `FileBufferingReadStream`: initially, the stream's Position and Length are both 0. Based on the code in [Stream.cs](https://github.com/dotnet/runtime/blob/ca074078a6f87bf24e473e868f8ea0616ab8f356/src/libraries/System.Private.CoreLib/src/System/IO/Stream.cs#L120-L156), CopyToAsync chooses a buffer size of 1.

Originally `CopyToAsync` was only fixed by updating the FileBufferingReadStream logic. But if we wrap the stream in another stream, the issue occurs again.

We are currently solving this issue by calling the overload of CopyToAsync that accepts an explicit buffer size.

### Expected Behavior

Expect the stream copy to use a default buffer of > 1 byte.

### Steps To Reproduce

```
var a = new TimedInputStream(fileBufferedReadStream);
await a.CopyToAsync(outputStream);
```

### Exceptions (if any)

_No response_

### .NET Version

_No response_

### Anything else?

_No response_