Try to fix BWC test (3)

Author: GalLalouche

x-pack/plugin/esql/qa/server/multi-clusters/src/javaRestTest/java/org/elasticsearch/xpack/esql/ccq/MultiClusterSpecIT.java

@@ -295,4 +295,9 @@ protected boolean supportsIndexModeLookup() throws IOException {
         // return hasCapabilities(List.of(JOIN_LOOKUP_V10.capabilityName()));
         return false;
     }
+
+    @Override
+    protected boolean supportsUnmappedFields() throws IOException {
+        return false;
+    }
 }