Add hh_state_update_race_fix flag

This is to prevent the race that's causing the HH state to be stuck in
connecting state.
Refer to the corresponding CL: ag/32298525

Bug: 403420458
Bug: 315241296
Test: m -j
Flag: com.android.bluetooth.flags.hh_state_update_race_fix
Change-Id: I78543fa98bc394774456c0edaa6b8fe8bdb917f2