[Security assistant] Fix Bedrock Langgraph ESQL tool calling

x-pack/plugins/elastic_assistant/server/lib/langchain/graphs/default_assistant_graph/index.ts

@@ -93,7 +93,7 @@ export const callAssistantGraph: AgentExecutor<true | false> = async ({
   const modelExists = await esStore.isModelInstalled();
 
   // Create a chain that uses the ELSER backed ElasticsearchStore, override k=10 for esql query generation for now
-  const chain = RetrievalQAChain.fromLLM(llm, esStore.asRetriever(10));
+  const chain = RetrievalQAChain.fromLLM(getLlmInstance(), esStore.asRetriever(10));
 
   // Check if KB is available
   const isEnabledKnowledgeBase = (await dataClients?.kbDataClient?.isModelDeployed()) ?? false;

x-pack/plugins/elastic_assistant/server/lib/langchain/graphs/default_assistant_graph/prompts.ts

@@ -28,7 +28,7 @@ export const geminiToolCallingAgentPrompt = ChatPromptTemplate.fromMessages([
   [
     'system',
     'You are a helpful assistant. ALWAYS use the provided tools. Use tools as often as possible, as they have access to the latest data and syntax.\n\n' +
-      `The final response will be the only output the user sees and should be a complete answer to the user's question, as if you were responding to the user's initial question, which is "{input}". The final response should never be empty.`,
+      "The final response will be the only output the user sees and should be a complete answer to the user's question, as if you were responding to the user's initial question. The final response should never be empty.",
   ],
   ['placeholder', '{chat_history}'],
   ['human', '{input}'],