nixos/frigate: Use find instead of rm for cleanup (#493138)

      serviceConfig = {

        ExecStartPre = [

          (pkgs.writeShellScript "frigate-clear-cache" ''

            shopt -s extglob

            rm --recursive --force /var/cache/frigate/!(model_cache)

            ${lib.getExe pkgs.findutils} /var/cache/frigate -not -path '/var/cache/frigate/model_cache/*' -type f -delete

          '')

          (pkgs.writeShellScript "frigate-create-writable-config" ''

            cp --no-preserve=mode ${configFile} /run/frigate/frigate.yml