Camera: Send shutter and result once per batch

For High Speed Recording, only send the shutter and result for the last
request in the batch, and count on the application process to derive
other results in the batch.

This reduces the binder transaction between the two processes, and saves
power.

Test: Manually test high speed recording with GCA, and CTS
Bug: 35775704
Change-Id: I3e1b4c1db3d1d1044400d825e2affa4461362b39