Revert "Multiple worker threads for SoundPool"

This reverts commit 7201d9cb6a5d9bcd4f82dfde32e25a1ca8e825e2.

This reduces CPU usage during Camera startup.

Bug: 38031165
Bug: 62447848
Change-Id: I857aefec9dd7566bfdd3b84873eb5d495449815c
2 files changed