Handle potential input / output truncation in DCR

• When generating AI code review comments, there's a risk that the response might get truncated if it exceeds max_tokens. This could lead to missing closing tags (e.g., </review>) and cause the system to behave as if there were no comments to display.
  • Additional context: !188117 (comment 2451424306)
• Once Update DCR prompt to include all diffs in one go (!188117 - merged) is merged, also investigate if we're exceeding token limits while sending all diffs in one-go.