refactor: update repair-diff.vm templates for both English and Chinese

- Add instruction to return only the modified code based on the original code and diff- Remove any additional content from the output

Author: phodal

core/src/main/resources/genius/en/code/repair-diff.vm

@@ -11,3 +11,5 @@ Here is the original code: ${context.oldCode}
 Here is the failed patched context:
 
 ${context.patchedCode}
+
+Just return code which based original code and the diff, do not add any other content.

core/src/main/resources/genius/zh/code/repair-diff.vm

@@ -11,3 +11,6 @@ Here is the original code: ${context.oldCode}
 Here is the failed patched context:
 
 ${context.patchedCode}
+
+Just return code which based original code and the diff, do not add any other content.
+