[Data] Fix signature of Rule.plan (ray-project#47094)

The method signature is missing self

python/ray/data/_internal/logical/interfaces/optimizer.py

@@ -6,7 +6,7 @@
 class Rule:
     """Abstract class for optimization rule."""
 
-    def apply(plan: Plan) -> Plan:
+    def apply(self, plan: Plan) -> Plan:
         """Apply the optimization rule to the execution plan."""
         raise NotImplementedError