Restrict Backup Import to Initialization Process and Refactor API Key Handling

[Ludy87]

Description of Changes

Please provide a summary of the changes, including:

• What was changed:

  • Updated the backup import logic in InitialSecuritySetup so that the database backup is only imported during initialization when there are no users present. If no backup exists, the admin user is initialized instead.
  • Refactored the API key addition in UserService by extracting the logic into a private helper method saveUser(Optional<User> user) and added a call to export the database after updating the user's API key.

• Why the change was made:

  • To prevent accidental or unintended backup imports outside the initialization process, ensuring the system only imports backups when necessary.
  • To improve code clarity and maintainability in the user API key management process, while ensuring that the database state is preserved via an export after key updates.

Closes #3057

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Checklist

General

• I have read the Contribution Guidelines
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• My changes generate no new warnings

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UI Changes (if applicable)

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Testing (if applicable)

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