22fa00455-1

Add the force flush function, which is used as follows:
select mo_debug('dn', 'flush','dbname.tablename');

Approved by: @XuPeng-SH, @ouyuanning, @daviszhen, @zhangxu19830126, @yingfeng, @nnsgmsone, @reusee, @aunjgr, @fengttt