examples: update all examples to use the new LLMContextAggregatorPair tuple

examples/foundational/20b-persistent-context-openai-realtime.py

@@ -215,16 +215,16 @@ Remember, your responses should be short. Just one or two sentences, usually."""
     llm.register_function("load_conversation", load_conversation)
 
     context = LLMContext([{"role": "user", "content": "Say hello!"}], tools)
-    context_aggregator = LLMContextAggregatorPair(context)
+    user_aggregator, assistant_aggregator = LLMContextAggregatorPair(context)
 
     pipeline = Pipeline(
         [
             transport.input(),  # Transport user input
             stt,  # STT
-            context_aggregator.user(),
+            user_aggregator,
             llm,  # LLM
             transport.output(),  # Transport bot output
-            context_aggregator.assistant(),
+            assistant_aggregator,
         ]
     )