fix(attach): use same route for public attachment requests

[max-nextcloud]

There are no separate public routes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.68%. Comparing base (468b46d) to head (cde33eb).
⚠️ Report is 15 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7478      +/-   ##
==========================================
- Coverage   59.69%   59.68%   -0.02%     
==========================================
  Files         495      495              
  Lines       37857    37844      -13     
  Branches     1090     1090              
==========================================
- Hits        22599    22586      -13     
  Misses      15151    15151              
  Partials      107      107              

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