nixos/services.mysql: remove legacy logic as old mysql version packages where droped (#508374)

  cfg = config.services.mysql;

  isMariaDB = lib.getName cfg.package == lib.getName pkgs.mariadb;

  isOracle = lib.getName cfg.package == lib.getName pkgs.mysql84;

  # Oracle MySQL has supported "notify" service type since 8.0

  hasNotify = isMariaDB || (isOracle && lib.versionAtLeast cfg.package.version "8.0");

  mysqldOptions = "--user=${cfg.user} --datadir=${cfg.dataDir} --basedir=${cfg.package}";

          superUser = if isMariaDB then cfg.user else "root";

        in

        ''

          ${lib.optionalString (!hasNotify) ''

            # Wait until the MySQL server is available for use

            while [ ! -e /run/mysqld/mysqld.sock ]

            do

                echo "MySQL daemon not yet started. Waiting for 1 second..."

                sleep 1

            done

          ''}

          ${lib.optionalString isMariaDB ''

            # If MariaDB is used in an Galera cluster, we have to check if the sync is done,

            # or it will fail to init the database while joining, so we get in an broken non recoverable state

      serviceConfig = lib.mkMerge [

        {

          Type = if hasNotify then "notify" else "simple";

          Type = "notify";

          Restart = "on-abnormal";

          RestartSec = "5s";