statistics: add multi-column index test cases for global-statas (#23265)
statistics: add multi-column index test cases for global-statas (#23265)


kyle-wang/tidb,pingcap/tidb,pingcap/tidb,ngaut/tidb,coocood/tidb,coocood/tidb,pingcap/tidb,ngaut/tidb,ngaut/tidb,c4pt0r/tidb,c4pt0r/tidb,c4pt0r/tidb,c4pt0r/tidb,pingcap/tidb,kyle-wang/tidb,ngaut/tidb,kyle-wang/tidb,pingcap/tidb,kyle-wang/tidb,kyle-wang/tidb,ngaut/tidb,ngaut/tidb,c4pt0r/tidb,kyle-wang/tidb,pingcap/tidb,c4pt0r/tidb