[Crash] Use the proxy in the audio callback

[danielebogo]

Rel #2420

This PR should fix the crash happening in the DefaultPlayer by using the new proxy for the audio callback

To test

• CI must be 🟢
• Try to play and change episodes while playing
• When the system decides to finalize the tap you will see 2 logs in this order:

1. The log from the finalize closure: [AudioProcessingTapProxy] Finalize tap: <MTAudioProcessingTap 0x6000030513b0> Retain count 3 Created with i/f/p/u/t callbacks = {0x10aa14448/0x10aa14600/0x10aa149b4/0x10aa14d08/0x10aa15330} flags = 0x1
2. The log from the proxy deinit: [AudioProcessingTapProxy] Deinit proxy

• Switch the FF off to check everything still works as before

Checklist

• I have considered if this change warrants user-facing release notes and have added them to CHANGELOG.md if necessary.
• I have considered adding unit tests for my changes.
• I have updated (or requested that someone edit) the spreadsheet to reflect any new or changed analytics.

[bjtitus]

✅ Checked streaming an episode with and without effects enabled
✅ Checked playing a downloaded episode with and without effects enabled

[SergioEstevao]

Looking good!