Revert "AudioMixer: Remove tracks from enabledTracks after reseting outTemp"

This reverts commit 0debbf6b029f0967241f2c48f3136f5ae91102f7, it's apparently the cause of the recent audio buffering issues with YT across multiple platforms.

Change-Id: I917da7cafff58878918881c0fde9fb90c5096b39
(cherry picked from commit 690f0ce48760dbafa29339896c235ffb43061025)