PSA: `AudioProcessingBuilder::Create(const webrtc::Config&)` will soon be removed

[Alessio Bazzica]

The old way to configure the WebRTC Audio Processing Module (APM) is being removed in https://webrtc-review.googlesource.com/c/src/+/232128 (expected to land on Tuesday September 21)

- Stop using `webrtc::Config` + `AudioProcessingBuilder::Create(const webrtc::Config&)`

- Instead use `webrtc::AudioProcessing::Config` and `AudioProcessing::ApplyConfig`