Resetting identity causes recovery set up issue

### Steps to reproduce

1. Log in to the app, set up a recovery key.
2. Log in again from scratch. This time, when asked to verify your identity during the onboarding process, choose "Reset identity."
3. On the room list page, in the setup banner, select "Set up recovery."
4. Choose "Generate new key."

### Outcome

It gets stuck on "Generating..."
This happens to me after every identity reset. To fix it, I have to go to the Element web application, delete the backup, and then I can regenerate a new one on the Android application.

Trying to delete the backup directly from the Android app by toggling off "Allow key storage" doesn't work.

While debugging the issue, I noticed that in RustEncryptionService, backupExistsOnServer() returns true. I think this is what causes the problem (you can't create a new key while the old one hasn't been deleted).

Additionally, I see that the state of the security key setup is stuck on "Starting," but there are no errors in the log.

### Your phone model

google pixel 8 pro

### Operating system version

android 16

### Application version and app store

google play store - version 25.06.2

### Homeserver

non-public

### Will you send logs?

No

### Are you willing to provide a PR?

No