Fix retrieval prompty to prevent nesting of reason/score/status under properties (#5055)

Inline the properties object and add explicit guidance so the LLM emits
reason, score, and status as top-level keys instead of nesting them
inside properties.

Author: m7md7sien

assets/evaluators/builtin/retrieval/evaluator/retrieval.prompty

@@ -86,7 +86,7 @@ CONTEXT: {{context}}
 ## Please provide your assessment Score for the previous CONTEXT in relation to the QUERY based on the Definitions above.
 
 Output a JSON object with:
-    1) properties: an object containing a "thought_chain" string. To improve the reasoning process, think step by step and include a step-by-step explanation of your thought process as you analyze the data based on the definitions. Keep it brief and start your thought_chain with "Let's think step by step:".
+    1) properties: an object containing ONLY a "thought_chain" string (do not include any other keys here). To improve the reasoning process, think step by step and include a step-by-step explanation of your thought process as you analyze the data based on the definitions. Keep it brief and start your thought_chain with "Let's think step by step:".
     2) reason: a very short explanation of why you think the input Data should get that Score.
     3) score: based on your previous analysis, provide your Score. The Score you give MUST be an integer score (i.e., "1", "2"...) based on the levels of the definitions.
     4) status: "completed" if evaluation was performed, or "skipped" if evaluation could not be performed.
@@ -98,12 +98,11 @@ If the QUERY or CONTEXT is empty or not provided, return status "skipped" immedi
 ```
 
 The reason should always precede the score and should clearly justify the score based on the rubric definitions.
-Response format exactly as follows:
+
+Response format exactly as follows ("reason", "score", and "status" MUST be top-level keys, NOT nested inside "properties". Note that "properties" is a single-line inline object — close its `}` immediately after `thought_chain` and then continue with the remaining top-level keys). Stop generating immediately after the final closing brace:
 
 {
-  "properties": {
-    "thought_chain": "Let's think step by step: <brief step-by-step analysis>"
-  },
+  "properties": { "thought_chain": "Let's think step by step: <brief step-by-step analysis>" },
   "reason": "<15-60 words>",
   "score": <1-5>,
   "status": "completed"