ddl: make test stable (#3091)
ddl: make test stable (#3091)


kyle-wang/tidb,ueizhou/tidb,EvilMcJerkface/tidb,c4pt0r/tidb,ngaut/tidb,anywhy/tidb,Cofyc/tidb,ueizhou/tidb,pingcap/tidb,simon-xia/tidb,cosmtrek/tidb,coocood/tidb,kyle-wang/tidb,CodeRushing/tidb,c4pt0r/tidb,zs634134578/tidb,yuanwhy/tidb,ngaut/tidb,EvilMcJerkface/tidb,astaxie/tidb,pingcap/tidb,pingcap/tidb,tiancaiamao/tidb,ming-relax/tidb,louishust/tidb,ngaut/tidb,wusphinx/tidb,coocood/tidb,mccxj/tidb,kyle-wang/tidb,XuHuaiyu/tidb,kyle-wang/tidb,ngaut/tidb,mccxj/tidb,pingcap/tidb,astaxie/tidb,8cbx/tidb,wusphinx/tidb,spongedu/tidb,kyle-wang/tidb,louishust/tidb,Nify/tidb,XuHuaiyu/tidb,gaocegege/tidb,cosmtrek/tidb,qiuyesuifeng/tidb,spongedu/tidb,pingcap/tidb,Nify/tidb,ngaut/tidb,8cbx/tidb,kyle-wang/tidb,anywhy/tidb,qiuyesuifeng/tidb,yangwenmai/tidb,c4pt0r/tidb,ming-relax/tidb,zs634134578/tidb,pingcap/tidb,tiancaiamao/tidb,zimulala/tidb,c4pt0r/tidb,silentred/tidb,yuanwhy/tidb,ngaut/tidb,yangwenmai/tidb,c4pt0r/tidb,c4pt0r/tidb,simon-xia/tidb,CodeRushing/tidb,zimulala/tidb,silentred/tidb,Cofyc/tidb,gaocegege/tidb