reduce potential duplicated call of `isCoveringIndex` (#13548)
reduce potential duplicated call of `isCoveringIndex` (#13548)


pingcap/tidb,Cofyc/tidb,ngaut/tidb,c4pt0r/tidb,ming-relax/tidb,kyle-wang/tidb,c4pt0r/tidb,ming-relax/tidb,kyle-wang/tidb,ngaut/tidb,ngaut/tidb,kyle-wang/tidb,EvilMcJerkface/tidb,c4pt0r/tidb,pingcap/tidb,EvilMcJerkface/tidb,kyle-wang/tidb,XuHuaiyu/tidb,kyle-wang/tidb,c4pt0r/tidb,Cofyc/tidb,ngaut/tidb,XuHuaiyu/tidb,kyle-wang/tidb,pingcap/tidb,pingcap/tidb,c4pt0r/tidb,ngaut/tidb,coocood/tidb,c4pt0r/tidb,pingcap/tidb,pingcap/tidb,coocood/tidb,ngaut/tidb