store/tikv: fix gc worker. (#4561)
store/tikv: fix gc worker. (#4561)


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