[fix][runtime] Fix issue that decimal type is not be truncated when scale is 0.

Author: nokiaMS

runtime/src/main/java/io/dingodb/expr/runtime/expr/Var.java

@@ -56,7 +56,7 @@ public Object eval(EvalContext context, ExprConfig config) {
                 return null;
             }
 
-            if (typeScale > 0) {
+            if (typeScale >= 0) {
                 return obj.setScale(typeScale, RoundingMode.HALF_UP);
             }
         }