refactor: Remove recent sprite changes from external_tileset

[thedyze]

Checklist

Required

• I wrote the PR title in conventional commit format.
• I ran the code formatter.
• I linked any relevant issues using github keyword syntax so it can be closed automatically.
• I have committed my changes to new branch that isn't main so it won't cause conflict when updating main branch later.

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Purpose of change

To cleanup after adding recent sprite changes as a mainline mod.

Describe the solution

Remove recent sprite changes from external_tileset as they now exist as a mod #5702

Describe alternatives you've considered

Testing

Additional context

Also removed changes added to tileset documentation