Duplicate and misplaced buttons appear during E2EE setup

### ⚠️ Before submitting, please verify the following: ⚠️

- [x] This is a **bug**, not a question or a configuration issue.
- [x] This issue is **not** already reported on Github (I have searched for it).
- [x] Nextcloud Server and Desktop Client are **up to date**. See [Server Maintenance and Release Schedule](https://github.com/nextcloud/server/wiki/Maintenance-and-Release-Schedule) and [Desktop Releases](https://nextcloud.com/install/#install-clients) for supported versions.
- [x] I agree to follow Nextcloud's [Code of Conduct](https://nextcloud.com/contribute/code-of-conduct/)

### Bug description

During the initial end-to-end encryption setup, one or two misplaced buttons remain visible in the account settings behind the mnemonic dialog. The exact appearance and number of misplaced buttons varies depending on the operating system and installation method.

After acknowledging and closing the mnemonic dialog, the account settings return to their normal appearance.

#### Linux development build:

#### macOS development build:

#### Official Linux AppImage:

### Steps to reproduce

The issue was reproduced in the following environments:

Linux: desktop client built with CMake from the master branch
Desktop Client 34.1.0-alpha
Pop!_OS 24.04 LTS

macOS: desktop client built with CMake from the master branch
Desktop Client 34.1.0-alpha
Taheo 26.6.2

Linux: official Nextcloud Desktop Client AppImage
Desktop Client 34.0.3
Pop!_OS 24.04 LTS

The following steps were used for each test:

Start a fresh Nextcloud server using Docker:

sudo docker run \
--name nc-e2ee-test \
--publish 8080:80 \
--env SQLITE_DATABASE=nextcloud.sqlite \
--env NEXTCLOUD_ADMIN_USER=admin \
--env NEXTCLOUD_ADMIN_PASSWORD=admin \
nextcloud

Install the End-to-End Encryption app:

sudo docker exec -u www-data nc-e2ee-test \
php occ app:install end_to_end_encryption

Enable the End-to-End Encryption app:

sudo docker exec -u www-data nc-e2ee-test \
php occ app:enable end_to_end_encryption

Connect the desktop client to http://localhost:8080.

Open the account settings and start the initial E2EE setup by selecting “Set up encryption”.

Observe the E2EE buttons in the account settings behind the mnemonic dialog.

### Expected behavior

While the mnemonic dialog is displayed, the buttons in the underlying account settings should remain correctly positioned. No obsolete or duplicate buttons should be visible.

### Which files are affected by this bug

No synchronized files are affected. This is a user-interface issue in the account settings during the initial E2EE setup.

### Operating system

Linux

### Which version of the operating system you are running.

Pop!_OS 24.04 LTS

### Installation method

Official Linux AppImage

### Nextcloud Server version

34.0.3.2

### Nextcloud Desktop Client version

34.1.0-alpha

### Did this occur after an update or on a clean installation?

Clean desktop client installation

### Are you using the Nextcloud Server Encryption module?

No

### Are you using an external user-backend?

- [x] Default internal user-backend
- [ ] LDAP or Active Directory
- [ ] SSO - SAML
- [ ] Other

### Nextcloud Server logs

```shell

```

### Additional info

_No response_

Reproduce the issue by following the Docker server setup and opening account settings during the initial E2EE setup. Start from the account-settings flow and mnemonic dialog, then trace how the underlying buttons are displayed while the dialog is open. Done means no obsolete, duplicate, or misplaced buttons are visible behind the dialog on the reported platforms.

Written by the indexing model from the issue text.