patch: remove usage of llm, chat model __call__ (#20788)

- `llm(prompt)` -> `llm.invoke(prompt)`
- `llm(prompt=prompt` -> `llm.invoke(prompt)` (same with `messages=`)
- `llm(prompt, callbacks=callbacks)` -> `llm.invoke(prompt,
config={"callbacks": callbacks})`
- `llm(prompt, **kwargs)` -> `llm.invoke(prompt, **kwargs)`

libs/community/langchain_community/llms/watsonxllm.py

@@ -320,7 +320,7 @@ class WatsonxLLM(BaseLLM):
         Example:
             .. code-block:: python
 
-                response = watsonx_llm("What is a molecule")
+                response = watsonx_llm.invoke("What is a molecule")
         """
         result = self._generate(
             prompts=[prompt], stop=stop, run_manager=run_manager, **kwargs