ddl: add more tests for expression index (#27037)
ddl: add more tests for expression index (#27037)

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