expr: fix unstable comparing push down fucntion result testcase  (#33655)
expr: fix unstable comparing push down fucntion result testcase  (#33655)

ref pingcap/tidb#31872
c4pt0r/tidb,c4pt0r/tidb,pingcap/tidb,ngaut/tidb,ngaut/tidb,pingcap/tidb,ngaut/tidb,c4pt0r/tidb,pingcap/tidb,c4pt0r/tidb,c4pt0r/tidb,ngaut/tidb,pingcap/tidb,pingcap/tidb,kyle-wang/tidb,kyle-wang/tidb,kyle-wang/tidb,kyle-wang/tidb,ngaut/tidb,kyle-wang/tidb,c4pt0r/tidb,kyle-wang/tidb,pingcap/tidb,ngaut/tidb