Remove two unused formats from Projects::TreeController#show

What does this MR do?

When viewing a tree in a project's repository, we use the Projects::TreeController#show endpoint for the overall view, and make background calls to Projects::RefsController#logs_tree endpoint to populate expensive N+1 data about each entry in the tree.

At some point, we called back to the #show endpoint to get this data instead, but that no longer seems to happen, making this dead code.

What are the relevant issue numbers?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Conforms to the database guides
• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer

Closes #38261 (closed)