remove broken packet_fuzzer target

This causes builds with line coverage to fail. It isn't actually needed
since each individual target should have its own cc_fuzz entry.

Bug: 157588276
Test: make haiku with NATIVE_LINE_COVERAGE=true NATIVE_COVERAGE=true COVERAGE_PATHS=*
Change-Id: Ib0df3e530aa107892c4e03bd4ef88a9caf26fde5