Drop unused python recording streams

[teh-cmc]

RecordingStreams created from Python have their lifetimes managed by the Rust SDK: this is important as we cannot have Drop implementations running at arbitrary points in time depending on what the Python GC happens to be doing.

The one downside to this is that these recordings are never really dropped, they are merely disconnected, which means e.g. their batching thread is still running for no reason.

In 99.9% of cases this is completely irrelevant since all these threads do is sleeping, but still it'd be nice to clean up at some point.