gl-testing: Disable cln-grpc plugin in test node factory

Disable the cln-grpc plugin for standard CLN test nodes created via
node_factory to prevent port conflicts with GL nodes. GL nodes already
have cln-grpc disabled in favor of gl-plugin, but standard test nodes
(e.g., created via node_factory.line_graph()) were still running
cln-grpc, which could cause port collisions during tests.

This ensures consistent behavior across all test nodes.

Author: claude

libs/gl-testing/gltesting/network.py

@@ -27,6 +27,8 @@ def get_node(self, options=None, *args, **kwargs):
             options = {}
         options["allow-deprecated-apis"] = True
         options["developer"] = None
+        # Disable cln-grpc plugin to avoid port conflicts with GL nodes
+        options["disable-plugin"] = "cln-grpc"
         return NodeFactory.get_node(self, options=options, *args, **kwargs)