`build_fuzzers --engine centipede` isn't compatible with local build directories

`helper.py` doesn't clean up build directories: https://github.com/google/oss-fuzz/issues/9249 so if build scripts don't do it themselves depending on the build system they can end up failing or reusing unsanitized builds when `helper.py` starts building sanitized builds for centipede. Even though the underlying issue is the same as https://github.com/google/oss-fuzz/issues/9249 I think this issue is different in that `helper.py` doesn't have to be run a few times in a row explicitly.

It's possible to get it around by cleaning up build directories explicitly or by switching to `podman` and applying the patch adding `:O` from https://github.com/google/oss-fuzz/issues/9249.