Don't add bottom 'match' line for deleted files

What does this MR do?

Skips bottom 'match' line for diffs of deleted files.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

If a file is deleted, its new_pos is 0 (less than total_blob_lines), but there is no reason to add the bottom 'match' line in this case because there is not extra content which could be expanded.

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a UX Designer
  • Has been reviewed by a Frontend maintainer
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• Internationalization required/considered
• End-to-end tests pass (package-and-qa manual pipeline job)

What are the relevant issue numbers?

Closes #48160 (closed)