fix(cfx-ui): allow closing auth modal when authentication failed

[DaniGP17]

Goal of this PR

Enable closing the login modal when authentication fails. Currently, the only way to exit the modal is by clicking the Try again button. This PR improves the user experience by allowing users to bypass that step when the auth service is unavailable.

How is this PR achieving the goal

Only returning true in the disabled getter when modal auth is processing and didn't get any error.

This PR applies to the following area(s)

FiveM

Successfully tested on

Platforms: Windows

Checklist

• [x] Code compiles and has been tested successfully.
• [x] Code explains itself well and/or is documented.
• [x] My commit message explains what the changes do and what they are for.
• [x] No extra compilation warnings are added by these changes.

Fixes issues

fixes #3440