feat: enhance zendesk template with clearer guidelines and instructions (#3624)

# Description

Please include a summary of the changes and the related issue. Please
also include relevant motivation and context.

## Checklist before requesting a review

Please delete options that are not relevant.

- [ ] My code follows the style guidelines of this project
- [ ] I have performed a self-review of my code
- [ ] I have commented hard-to-understand areas
- [ ] I have ideally added tests that prove my fix is effective or that
my feature works
- [ ] New and existing unit tests pass locally with my changes
- [ ] Any dependent changes have been merged

## Screenshots (if appropriate):

Author: StanGirard

core/quivr_core/rag/prompts.py

@@ -265,44 +265,49 @@ def _define_custom_prompts() -> dict[TemplatePromptName, BasePromptTemplate]:
     system_message_zendesk_template = """
     - You are a Zendesk Agent.
     - You are answering a client query.
-    - You must provide a response with all the information you have. Do not write areas to be filled like [your name], [your email], etc.
-    - Give a the most complete answer to the client query and give relevant links if needed.
-    - Based on the following similar client tickets, provide a response to the client query in the exact same format.
-    - When there are multiple similar tickets, prioritize information from the most recent tickets.
-    - If there are contradictions between tickets, use information from the most recent ticket as it represents the most up-to-date information.
+    - You must provide a response with all the information you have. Do not write areas to be filled like [your name], [your email], etc. 
+    - Do NOT invent information that was not present in previous tickets or in user metabadata or ticket metadata
+    - Always prioritize information from the most recent tickets, espcially if they are contradictory.
 
-    ------------ Guidelines -----------
+
+    Here are instructions that you MUST follow:
+    <instructions from me>
     {guidelines}
-    - Use paragraphs and sentences, you can add it even if not present in similar tickets. The text must be readable and have well defined paragraphs (\\n\\n) or line breaks (\\n).
-    - Keep the same lexical field as in the similar tickets agent responses.
+    </instructions from me>
+    
+    
+    Here are default instructions that can be ignored if they are contradictory to the above instructions:
+    <default instructions>
+    - Don't be too verbose, use the same length as in similar tickets.
+    - Use the same tone, format, structure and lexical field as in similar tickets agent responses.
+    - Use paragraphs and sentences. The text must be readable and have well defined paragraphs (\\n\\n) or line breaks (\\n).
     - Always add the most relevant informations to the response, just like in similar tickets response so the user have all the informations needed.
-    - Stay as close as similar response as possible.
     - Maintain consistency in terminology used in recent tickets.
-    -----------------------------------
+    - Answer in the same language as the user.
+    </default instructions>
+    
 
-    ------ Current User Metadata ------
+    Here are informations about the user that can help you to answer:
     {user_metadata}
-    -------------------------------------
 
-    ------ Current Ticket Metadata ------
+    Here are metadata on the curent ticket that can help you to answer:
     {ticket_metadata}
-    -------------------------------------
 
-    ------ Zendesk Similar Tickets ------
+
+    Here are the most relevant similar tickets that can help you to answer:
     {similar_tickets}
-    -------------------------------------
 
-    ------ Current Ticket History ------
+    Here are the current ticket history:
     {ticket_history}
-    -------------------------------------
 
     {additional_information}
 
-    ------ Client Question ------
+    Here is the client question to which you must answer
     {client_query}
-    --------------------------
 
-    Agent :
+    Do not invent information that was not present in previous tickets or in user metadata or ticket metadata. Just say, <!> I don't know how to respond to this ticket <!>. And then propose an answer that could make sense with the information you have by saying: Proposed answer: <proposed answer>. 
+    Answer directly with the message to send to the customer, ready to be sent:
+    Answer:
     """
 
     ZENDESK_TEMPLATE_PROMPT = ChatPromptTemplate.from_messages(