message: fix(db2): change name and add legacy alias
diff: @@ -18,7 +18,8 @@ from superset.db_engine_specs.base import BaseEngineSpec, LimitMethod
  class Db2EngineSpec(BaseEngineSpec):
  - engine = "ibm_db_sa"
  + engine = "db2"
  + engine_aliases = ("ibm_db_sa",)
  engine_name = "IBM Db2"
  limit_method = LimitMethod.WRAP_SQL
  force_column_alias_quotes = True
  