Fix blob edit controls layout and cut off borders

What does this MR do and why?

1. Automatic migration with scripts/frontend/migrate_to_container_queries.mjs
2. Adjusts the layout of editor controls on narrow and mid-sized viewports, both with and without panel feature flags. This corrects a wonky layout that's already present.
3. Makes sure .file-title doesn't hide rounded border

References

• https://gitlab.com/gitlab-org/gitlab/-/issues/570037+
• https://docs.gitlab.com/development/fe_guide/style/scss/#migrating-from-media-queries

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Go to a project and open a file. Best is a markdown file, as it will have all the controls.
2. Click Edit button, then select Edit single file from the dropdown. You'll be redirected to the editor.
3. Toggle Duo panel, change browser's width and verify changes.

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 #570037