stub in field attribute

Author: not-napoleon

x-pack/plugin/esql-core/src/main/java/org/elasticsearch/xpack/esql/core/expression/FieldAttribute.java

@@ -206,6 +206,11 @@ protected String label() {
         return "f";
     }
 
+    @Override
+    public boolean isDimension() {
+        return false;
+    }
+
     public EsField field() {
         return field;
     }