[DOP-19779] Delete user modification endpoints

[IlyasDevelopment]

Change Summary

Since integration with an external authentication system (SSO, LDAP) is planned, where the name cannot be changed simply like that and the user activity is checked at the moment of authentication by means of the external system itself, the following routes are deleted:
PATCH /v1/user/:id
POST /v1/user/activate
POST /v1/user/deactivate

Checklist

• Commit message and PR title is comprehensive
• Keep the change as small as possible
• Unit and integration tests for the changes exist
• Tests pass on CI and coverage does not decrease
• Documentation reflects the changes where applicable
• docs/changelog/next_release/<pull request or issue id>.<change type>.rst file added describing change
  (see CONTRIBUTING.rst for details.)
• My PR is ready to review.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.77%. Comparing base (b9e138f) to head (09b073f).
Report is 91 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop      #90      +/-   ##
===========================================
- Coverage    92.95%   92.77%   -0.19%     
===========================================
  Files           84       84              
  Lines         2456     2435      -21     
  Branches       308      301       -7     
===========================================
- Hits          2283     2259      -24     
- Misses         121      125       +4     
+ Partials        52       51       -1     

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