CSharp telemetry evolution - OTel Exporter and ActivityListener implementations

@birschick-bq How do you see this evolving as time goes on? It sounds like the file exporter in the `Listeners` project isn't fully compatible with the one in the `Exporters` project -- so switching to `Exporters` would be a breaking change? Then any new C#-based driver would have to decide which of the two to use/support?

_Originally posted by @CurtHagenlocher in https://github.com/apache/arrow-adbc/issues/3315#issuecomment-3330338792_

Need to address the evolution of telemetry observation possibilities in the CSharp implementation.

Currently, there are two implementations.
- based on the [OTel Exporters](https://github.com/apache/arrow-adbc/tree/main/csharp/src/Telemetry/Traces/Exporters#readme) interface
- base on the [ActivityListener](https://github.com/apache/arrow-adbc/tree/main/csharp/src/Telemetry/Traces/Listeners#readme) interface

1. Does it make sense to have two implementations?
2. Can a driver leverage both implementations?
3. What strengths and weaknesses does each implementation bring?

Start by reading the README files and interfaces under csharp/src/Telemetry/Traces/Exporters and csharp/src/Telemetry/Traces/Listeners. Compare the OTel Exporters and ActivityListener implementations, including whether a driver can use both. Done means reaching and documenting a decision about whether both should remain and how new C# drivers should support them.

Written by the indexing model from the issue text.