Summary

Refactored the audio recording pipeline in AssistViewModelBase to fix a race condition when buffering audio data before STT is ready.

The issue was mostly seen when using a watch, but also on other low end devices. The issue was that the queue was nullify before all the data were fully sent. The new approach is to use a channel to store the data and make sure that we only use this to send the data. We only send the data when we reach the SST_START event.

Checklist

• New or updated tests have been added to cover the changes following the testing guidelines.
• The code follows the project's code style and best_practices.
• The changes have been thoroughly tested, and edge cases have been considered.
• Changes are backward compatible whenever feasible. Any breaking changes are documented in the changelog for users and/or in the code for developers depending on the relevance.

Any other notes

Based on #6188.
Fixes #6048