GATT start timeout

Some tests fail occasionally due to the length of time required to
start GATT taking longer than the length of time allotted for a
context switch. Allow for 500ms.

Bug: 149857512
Test: atest BluetoothInstrumentationTests
Change-Id: Id8a29a3cca97e830e771f59b3233065c26d15447
1 file changed