Randomize media ID to correct lost audio focus fix

This change creates a new state machine outside of set up so that it
follows the corresponding flag rule for BrowseTree when created.

Tag: #stability
Bug: 215263047
Bug: 332367017
Flag: EXEMPT, test change only
Test: atest AvrcpControllerStateMachineTest.java
Change-Id: I0a8dc727475c700e7fc2fe99fe6aed27496ed29d