AudioPolicy: Fix music stutter when device connect

Added a check for invalid client descriptors to prevent setting invalidate repeatedly on an invalid track

BUG: 381009246
Test:Manual
1. a2dp non-offload playback music
2. insert 3.5 mm headset
(cherry picked from https://partner-android-review.googlesource.com/q/commit:2f183214ffffa727f9ceef1bbf65e92e1b7b2bfc)
Flag: EXEMPT bug fix
Merged-In: I16ebf953fc9f65d13f680205173c3365c7e01875
Change-Id: I16ebf953fc9f65d13f680205173c3365c7e01875