feat(tianmu): add multi-thread aggregation of group by (stoneatom#422)…

… (stoneatom#1279)

Documentation for mysql aggregation
    https://dev.mysql.com/doc/refman/8.0/en/aggregate-functions-and-modifiers.html

    Functional Requirements:
    Consistent with aggregation conditions handled by existing logic
    The Aggregate function is used as the entry and ResultSender is used as the result output
    Performance Requirements:
    Table data limit:
    The upper limit of a physical drive
    The memory limit is exceeded. Procedure
    Memory usage limit:
    Add parameters to control the maximum amount of memory that can be used for aggregation
    Otherwise temporary disk files if the limit is exceeded
    Execution time limit:
    Under the same conditions, it is in the same order of magnitude as InnoDB aggregate query at most
    Aim to take less time than InnoDB for aggregated queries

mysql-test/include/default_mysqld.cnf

@@ -81,3 +81,7 @@ loose-show-compatibility-56=ON
 
 tianmu_insert_delayed = 0
 tianmu_ini_allowmysqlquerypath=1
+tianmu_groupby_parallel_degree=0
+tianmu_force_hashjoin=0
+tianmu_join_parallel=0
+