移除无用prompt，优化replyer回复表现

prompts/en-US/hippo_topic_summary.prompt

@@ -1,22 +0,0 @@
-Please summarize the following chat record segment based on the topic and extract the following information:
-
-**Topic**: {topic}
-
-**Requirements**:
-1. Keywords: extract keywords related to the topic and return them as a list (3-10 keywords)
-2. Summary: provide a plain-text summary of this segment (50-200 words). Requirements:
-   - Carefully retell the event and the chat content;
-   - Highlight the development process and the result of the event;
-   - Summarize around the central topic;
-   - Extract the key information points in the topic, and keep them concise and clear.
-
-Please return in JSON format as follows:
-{{
-    "keywords": ["keyword1", "keyword2", ...],
-    "summary": "summary content"
-}}
-
-Chat record:
-{original_text}
-
-Please return JSON directly and do not include any other content.