Unify the bucket directory name for target binary in `target_experime…

…nt.py` (google#11713)

Related: google/oss-fuzz-gen#172, google#11700.
This simplifies the link generation in benchmark `JSON`.
Previously, the binary directory name matches the binary name, now it is
always called `target_binary/`.

infra/build/functions/target_experiment.py

@@ -138,7 +138,7 @@ def run_experiment(project_name, target_name, args, output_path,
              f'find {build.out} -type f -name {target_name} -exec bash -c '
              f'\'cp "$0" "{local_target_dir}/$(echo "$0" | sed "s@/@_@g")"\' '
              f'{{}} \\; && gsutil cp -r {local_target_dir} '
-             f'{upload_reproducer_path}/{target_name} || true'),
+             f'{upload_reproducer_path}/target_binary || true'),
         ],
     })