Camera: Drain attached and queued input buffers during reconfiguration

Application may first call ImageWriter.queueInputImage without sending any capture
request before reconfiguring capture session using the same ImageWriter.
In this case, the stale buffers still exist in the buffer qeueue, and
ImageWriter.queueInputImage may stuck at waiting for free slots in the
new capture session.

Clear up all such queued buffers in the input buffer queue during stream
reconfiguration.

Test: Run testMandatoryReprocessConfigurations 300 times
Test: testQueueImageWithoutRequest
Bug: 138729150
Change-Id: Ie102dd018983bbd972f7c647d8c86c976a44e754