executor: add unit test for aggfuncs (#7966)
executor: add unit test for aggfuncs (#7966)


pingcap/tidb,kyle-wang/tidb,ngaut/tidb,ngaut/tidb,kyle-wang/tidb,tiancaiamao/tidb,Cofyc/tidb,EvilMcJerkface/tidb,pingcap/tidb,c4pt0r/tidb,kyle-wang/tidb,mccxj/tidb,c4pt0r/tidb,XuHuaiyu/tidb,ming-relax/tidb,ngaut/tidb,c4pt0r/tidb,qiuyesuifeng/tidb,tiancaiamao/tidb,c4pt0r/tidb,kyle-wang/tidb,coocood/tidb,EvilMcJerkface/tidb,XuHuaiyu/tidb,coocood/tidb,ngaut/tidb,mccxj/tidb,c4pt0r/tidb,pingcap/tidb,pingcap/tidb,cosmtrek/tidb,ming-relax/tidb,kyle-wang/tidb,pingcap/tidb,ngaut/tidb,c4pt0r/tidb,qiuyesuifeng/tidb,Cofyc/tidb,cosmtrek/tidb,kyle-wang/tidb,pingcap/tidb,ngaut/tidb