Resolve "Web IDE: syntax highlighting after re-naming a file doesn't work"

What does this MR do?

Resolves #31858 (closed).

References https://gitlab.com/gitlab-org/gitlab-ee/issues/31058

The MR is based upon https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/16539.

It re-enables syntax highlighting for entries after they are renamed.

Example of the renaming of the .editorconfig file that is a plain text by default:

	Before	After
rename to .editorconfig.md
rename to .editorconfig.js

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.