[fix](planner) NPE when use ctas to create table (#18973)

This is caused by expr in orderbyelements is not analyzed.

fe/fe-core/src/main/java/org/apache/doris/analysis/FunctionCallExpr.java

@@ -1630,6 +1630,11 @@ public class FunctionCallExpr extends Expr {
         }
         // rewrite return type if is nested type function
         analyzeNestedFunction();
+        for (OrderByElement o : orderByElements) {
+            if (!o.getExpr().isAnalyzed) {
+                o.getExpr().analyzeImpl(analyzer);
+            }
+        }
     }
 
     // if return type is nested type, need to be determined the sub-element type