'Registration is disabled' error stops OIDC registrations

### Steps to reproduce

1. Where are you starting? What can you see?

Unauthenticated welcome screen upon first downloading app

2. What do you click?

Pressing 'create account', then entering a homeserver - specifically one that delegates identity to an OIDC provider and disables native registrations.

### Outcome

#### What did you expect?

The homeserver should be validated and the user should be given a button 'Continue to '. This is what happens if the user follows the same steps after clicking 'I already have an account'.

#### What happened instead?


Validation returns error 'registration is disabled'. This behaviour differs from the iOS app.

### Your phone model

Pixel 5

### Operating system version

_No response_

### Application version and app store

_No response_

### Homeserver

radical.directory

### Will you send logs?

Yes

### Are you willing to provide a PR?

Yes