Delay A2DP HAL out stream open process

Delay A2DP HAL out stream open process to ensure that the
Headset is in proper state when START is initiated from DUT
immediately after the connection due to ongoing music playback.
Jawbone speaker goes to bad state unless it gets enough time
between AVDTP OPEN and START.

Bug: 22028876
Change-Id: I79a895a85ac7d37208192acf9064fd5c979dd28b