Remove 'use_libfuzzer' from zlib fuzzer

We want to minimize use of 'use_libfuzzer' since fuzzers are also built
with AFL and (in future) centipede fuzzing engines too.

This may result in more bugs being found using AFL already, but will be
especially important as we move from libfuzzer to centipede.

Bug: 1369919
Change-Id: Iec7f4e3a514438182f640fdfc3dc5e3cf4dd47bc
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4291744


Reviewed-by: Adrian Taylor <adetaylor@chromium.org>
Reviewed-by: Adam Langley <agl@chromium.org>
Commit-Queue: Adrian Taylor <adetaylor@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1116897}
NOKEYCHECK=True
GitOrigin-RevId: 504c1e4aa5e81e744ecd34653a37daaab42cc93d