public List<TSeriesPartitionSlot> filterUnassignedSchemaPartitionSlots(
      List<TSeriesPartitionSlot> partitionSlots) {
    return schemaPartitionTable.filterUnassignedSchemaPartitionSlots(partitionSlots);
  }
Only Leader use this interface. Filter unassigned SchemaPartitionSlots within the specific
StorageGroup.

@param partitionSlots List<TSeriesPartitionSlot>
@return Unassigned PartitionSlots
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/persistence/partition/DatabasePartitionTable.java