[zircon][gn] Remove noop-test.fuzzer from build-tests

The compiler doesn't actually support -fsanitize=fuzzer builds
that supply their own main function instead of getting it from
libfuzzer.  This was not noticed because build-tests isn't getting
run on bots.

Bug: BLD-481 #done
Change-Id: I2575cf987ff083843b22edebb28bd7bcf2525ae3