[minor](Nereids): add toString() for LogicalProperties (#19851)

fe/fe-core/src/main/java/org/apache/doris/nereids/properties/LogicalProperties.java

@@ -107,6 +107,19 @@ public class LogicalProperties {
         return new LogicalProperties(Suppliers.ofInstance(output), nonUserVisibleOutputSupplier);
     }
 
+    @Override
+    public String toString() {
+        return "LogicalProperties{"
+                + "\noutputSupplier=" + outputSupplier.get()
+                + "\nnonUserVisibleOutputSupplier=" + nonUserVisibleOutputSupplier.get()
+                + "\noutputExprIdsSupplier=" + outputExprIdsSupplier.get()
+                + "\noutputSetSupplier=" + outputSetSupplier.get()
+                + "\noutputMapSupplier=" + outputMapSupplier.get()
+                + "\noutputExprIdSetSupplier=" + outputExprIdSetSupplier.get()
+                + "\nhashCode=" + hashCode
+                + '}';
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) {

fe/fe-core/src/main/java/org/apache/doris/nereids/trees/expressions/SlotReference.java

@@ -176,10 +176,6 @@ public class SlotReference extends Slot {
         return this;
     }
 
-    public SlotReference withDataType(DataType dataType) {
-        return new SlotReference(exprId, name, dataType, nullable, qualifier, column);
-    }
-
     public SlotReference withNullable(boolean newNullable) {
         if (this.nullable == newNullable) {
             return this;