[PSM Interop] Enable xDS custom LB test for Node (#34146)

v1.10.x is the next version, so this will only run on master for now.
This won't work until grpc/grpc-node#2555 is merged.

Author: murgatroid99

tests/custom_lb_test.py

@@ -59,6 +59,8 @@ def is_supported(config: skips.TestConfig) -> bool:
             return config.version_gte("v1.55.x")
         if config.client_lang == _Lang.GO:
             return config.version_gte("v1.56.x")
+        if config.client_lang == _Lang.NODE:
+            return config.version_gte("v1.10.x")
         return False
 
     def test_custom_lb_config(self):