TruffleRuby build definitions used to explicitly rely on `brew --prefix openssl@1.1` on macOS and abort installation if that was not found. However, this check didn't take into account that the user might have set OPENSSL_PREFIX in their environment, or that they have another `openssl@*` version installed via Homebrew. This change removes the `use_homebrew_openssl` check and allows TruffleRuby to perform its own OpenSSL detection.
https://github.com/oracle/truffleruby/blob/vm-23.1.0/lib/truffle/truffle/openssl-prefix.rb#L14-L17
* The openssl built by ruby-build was not used by TruffleRuby,
and causes https://github.com/oracle/truffleruby/issues/1818
* Improve error message when openssl from Homebrew is not available.
* Change the definition code so it checks the operating system too.
