Resolve "Claude 4.0 Sonnet Merge Request Summary"

What does this MR do and why?

refer to !182958 (merged) and gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!2051 (diffs)

gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!2066 (merged) and !183213 (merged)

this MR should be reviewed together with gitlab-org/modelops/applied-ml/code-suggestions/ai-assist!2670 (merged)

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

[5] pry(main)> Feature.enable(:summarize_new_merge_request_claude_4_0_rollout)

click on edit and click on summarize code changes:

and check the log of AIGW: and find that Claude 4.0 Summarize New Merge Request

2025-06-05 16:24:26 [info     ] Returning prompt from the registry correlation_id=01JX0W8CCX72SS52A1TQ03D9R3 prompt_id=summarize_new_merge_request/base prompt_name='Claude 4.0 Summarize New Merge Request' prompt_version=2.1.0

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Related to #545504 (closed)