Remove logging when metadata tag can't be found.

This logging is expensive when it happens at 30fps (measured at around
0.5 mW per such message @30fps). Furthermore, no such logging happens in
the SDK when a tag can't be found, so this is simply aligning the
NDK's behavior with the SDK's.

Bug: 290694535
Test: built and confirmed power reduction.

Change-Id: I2b5397aa79fb176d90678a30550af08872b29a20