Avoid unnecesary `force_encoding` operations

What does this MR do?

Avoind unnecesary force_encoding operations

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

No

Why was this MR needed?

As gitaly#267 (comment 32146023) shows, force_encoding operations can be quite taxing from a performance point of view. Avoiding them when they're not required can saves us time.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #39227 (closed)