Limit allowed commit range for Changelog generation

What does this MR do and why?

• Contributes to #340941
• Feature flag: #364101

We want to verify the commit range before fetching the commits to keep a good endpoint performance.

Screenshots or screen recordings

How to set up and validate locally

1. Enable feature flag Feature.enable(:changelog_commits_limitation)
2. Find a project id that has more than 15000 commits (or lower COMMITS_LIMIT constant locally)
3. Visit URL: http://127.0.0.1:3000/api/v4/projects/<project_id>/repository/changelog?version=v1.0&from=<from_sha>&to=<to_sha>
4. You should see an error that the commit range is over the limit

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.