Remove obsolete reset_admin_password function

[msk]

This PR removes the reset_admin_password function from the graphql::account module, as it has been obsoleted by the resetAdminPassword GraphQL API mutation.

The reset_admin_password function was previously used by the QUIC API, but since the QUIC API has been replaced with the GraphQL API mutation instead, this function is no longer needed.

Note: CI is currently failing due to a Clippy warning, but this will be resolved once #385 is merged.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.34%. Comparing base (3aebb1b) to head (7dd139d).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #386      +/-   ##
==========================================
+ Coverage   71.32%   71.34%   +0.01%     
==========================================
  Files          67       67              
  Lines       14666    14657       -9     
==========================================
- Hits        10461    10457       -4     
+ Misses       4205     4200       -5     

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