code: public static String suffixHSIdsWithMigratePartitionLeaderRequest(Long HSId) {
          return Long.toString(Long.MAX_VALUE) + "/" + Long.toString(HSId) + migrate_partition_leader_suffix;
      }
docs: Generate a HSID string with BALANCE_SPI_SUFFIX information.
  When this string is updated, we can tell the reason why HSID is changed.