fix(mobile): Server endpoint on the login screen.

[jpros]

Description

On the Immich iOS app, the server url upon logout is stored with the /api endpoint, which we no longer expose to / expect the user to set.

On the login screen, after logout, it added the "/api" suffix instead of using the default method getServerUrl, which takes care of sanitizing the URL.

Fixes #15951

How Has This Been Tested?

Logged in as regular, logged out, the Server URL now is without the API endpoint.

Checklist:

• I have performed a self-review of my own code
• I have made corresponding changes to the documentation if applicable
• I have no unrelated changes in the PR.
• I have confirmed that any new dependencies are strictly necessary.
• I have written tests for new code (if applicable)
• I have followed naming conventions/patterns in the surrounding code
• All code in src/services uses repositories implementations for database calls, filesystem operations, etc.
• All code in src/repositories/ is pretty basic/simple and does not have any immich specific logic (that belongs in src/services)

[alextran1502]

Hello, have you tried login/logout to different instances with different accounts?

[jpros]

@alextran1502 I tried with 2 different accounts on the same server, both went fine.

I used the same method that is currently being used by the menu screen.