Remove unhelpful ExceptionDescribe from DDMS error path.

If a DDMS handler threw an error or returned invalid input we would
call ExceptionDescribe on the exception. This is usually not very
helpful since it goes to System.err instead of logcat and can make
testing difficult. This change replaces the ExceptionDescribe with a
LOG(INFO).

Test: ./test.py --host -j50
Bug: 70988713
Change-Id: I41e743c42e63c0dcb6d32473c31f391983819d32