fix: endless redirection loop between /user/settings/change_password and /user/settings/security (#10002)

Fixes forgejo/forgejo#9980

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### Tests

- I added test coverage for Go changes...
  - [ ] in their respective `*_test.go` for unit tests.
  - [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I added test coverage for JavaScript changes...
  - [ ] in `web_src/js/*.test.js` if it can be unit tested.
  - [ ] in `tests/e2e/*.test.e2e.js` if it requires interactions with a live Forgejo server (see also the [developer guide for JavaScript testing](https://codeberg.org/forgejo/forgejo/src/branch/forgejo/tests/e2e/README.md#end-to-end-tests)).

### Documentation

- [ ] I created a pull request [to the documentation](https://codeberg.org/forgejo/docs) to explain to Forgejo users how to use this change.
- [x] I did not document these changes and I do not expect someone else to do it.

### Release notes

- [ ] I do not want this change to show in the release notes.
- [x] I want the title to show in the release notes with a link to this pull request.
- [ ] I want the content of the `release-notes/<pull request number>.md` to be be used for the release notes instead of the title.

<!--start release-notes-assistant-->

## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Bug fixes
  - [PR](https://codeberg.org/forgejo/forgejo/pulls/10002): <!--number 10002 --><!--line 0 --><!--description ZW5kbGVzcyByZWRpcmVjdGlvbiBsb29wIGJldHdlZW4gL3VzZXIvc2V0dGluZ3MvY2hhbmdlX3Bhc3N3b3JkIGFuZCAvdXNlci9zZXR0aW5ncy9zZWN1cml0eQ==-->endless redirection loop between /user/settings/change_password and /user/settings/security<!--description-->
<!--end release-notes-assistant-->

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/10002
Reviewed-by: Mathieu Fenniak <mfenniak@noreply.codeberg.org>
Co-authored-by: zokki <zokki.softwareschmiede@gmail.com>
Co-committed-by: zokki <zokki.softwareschmiede@gmail.com>

models/fixtures/TestTwoFactorWithPasswordChange/user.yml

@@ -0,0 +1,37 @@
+-
+  id: 2001
+  lower_name: user2001
+  name: user2001
+  full_name: "user2001"
+  email: user2001@example.com
+  keep_email_private: false
+  email_notifications_preference: onmention
+  passwd: ZogKvWdyEx:password
+  passwd_hash_algo: dummy
+  must_change_password: true
+  login_source: 0
+  login_name: user2001
+  type: 0
+  salt: ZogKvWdyEx
+  max_repo_creation: -1
+  is_active: true
+  is_admin: false
+  is_restricted: false
+  allow_git_hook: false
+  allow_import_local: false
+  allow_create_organization: true
+  prohibit_login: false
+  avatar: ""
+  avatar_email: user2001@example.com
+  use_custom_avatar: true
+  num_followers: 0
+  num_following: 0
+  num_stars: 0
+  num_repos: 0
+  num_teams: 0
+  num_members: 0
+  visibility: 0
+  repo_admin_change_team_access: false
+  theme: ""
+  keep_activity_private: false
+  created_unix: 1759086716