Prevent Thread Leaks in STMiddleware

We create threads which are never quit in several utilities in
SoundTriggerMiddleware leading to performance issues.

Appropriately gate their life time via detach.

Bug: 236788273
Test: atest UptimeTimerTest.java
Test: atest SoundTriggerHalConcurrentCaptureHandlerTest.java
Test: Manual Logging verification
Change-Id: I478825ef50c9d6d539ecc93ad0bab16092f17152