refactor(langchain)!: remove SummarizeDocument built-in action

Remove the built-in SummarizeDocument action which relied on deprecated
LangChain Chain features. Users who need document summarization should
implement custom actions using LangChain Runnable chains.

- Delete nemoguardrails/actions/summarize_document.py
- Remove related import from llm/filters.py

Author: Pouyanpi

nemoguardrails/actions/summarize_document.py

@@ -50,7 +50,6 @@ def co_v2(
         "retrieve_relevant_chunks",
         "create_event",
         "wolfram alpha request",
-        "summarize_document",
         "apify",
         "bing_search",
         "google_search",