Avoid AudioManager#getMode in isFilterMatched

AudioManager#getMode is a slow binder call which should not be called on
UI thread. isFilterMatched will be frequently triggered on UI thread when updating the
Connected devices page.

Cache and update the audio mode when receive onModeChanged callback in
this change. For long term, we should better separate the UI/background
thread tasks in those classes. Also send request to Audio team to
improve the API latency.

Flag: EXEMPT small fix
Bug: 380993178
Test: atest
Change-Id: I054f3fa62f0fdf03b9a436a532ac1fb4738aaf58