planner: fix two test cases that use the wrong collation name (#27329)
planner: fix two test cases that use the wrong collation name (#27329)

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