Ignore logs less than warning on fuzz builds

It slows down fuzzing and prevents you from seeing fuzzer output.
Not needed, especially during automated fuzzing.

Create variant of libbluetooth_gd with this turned on.

Test: gd/fuzzing/run --host bluetooth_gd_hci_fuzz_test
Change-Id: I648894c41669b3a34d3ed937ede4f5524aff2d00