Relax NNAPI QoS deadline parameter

Prior to this CL, the NNAPI QoS deadline is a strict deadline: a task
with a deadline must either complete or abort by the deadline. To
avoid as much overhead as possible, it is requested for Android R to
have a relaxed deadline, where the task *may* be aborted after the
deadline has passed or when the task is estimated to take too long.

Because the deadline is now relaxed, the querying method
IDevice::supportsDeadlines can be removed.

Bug: 149766387
Test: mma
Test: VtsHalNeuralnetworksV1_3TargetTest
Change-Id: Ib9937b5bb95646c2fd82e1aa17f2b0b639e2c420