fix(datax): mysql_reader 去掉已删的 mysql_utils.MySQLColumn import

dw_base/database/ 于 2026-04-21 整目录删除（kb/92 L154），mysql_reader
顶层 import MySQLColumn 成破损链，plugin_factory 一旦加载就挂。
删 import + 两处 type hint List[MySQLColumn] 降为 List；方法体保留
（仅被 gc-generator 调用、本轮不重写，按 kb/90 §2.7 拆除时再一并删）

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

dw_base/datax/plugins/reader/mysql_reader.py

@@ -5,7 +5,6 @@ from configparser import ConfigParser
 from typing import Dict, List
 
 from dw_base.common.template_constants import MYSQL_HIVE_CREATE_TABLE_TEMPLATE, MYSQL_HIVE_HBASE_CREATE_TABLE_TEMPLATE
-from dw_base.database.mysql_utils import MySQLColumn
 from dw_base.datax.datax_constants import *
 from dw_base.datax.plugins.reader.reader import Reader
 from dw_base.utils.datetime_utils import local_2_utc, parse_datetime
@@ -196,7 +195,7 @@ class MySQLReader(Reader):
                           hive_table_name: str,
                           table_comment: str,
                           partitioned: bool,
-                          columns: List[MySQLColumn],
+                          columns: List,
                           column_types: Dict[str, str]) -> str:
         columns_definition = []
         partition_def = ''
@@ -224,7 +223,7 @@ class MySQLReader(Reader):
                                      table_comment: str,
                                      hbase_namespace: str,
                                      hbase_table_name: str,
-                                     columns: List[MySQLColumn],
+                                     columns: List,
                                      column_types: Dict[str, str]) -> str:
         columns_definition = []
         hbase_column_mapping_definition = []