Key Backup not working after Cross signing

### Steps to reproduce

1. Have a valid Element Web Session with Key Backup set up.
2. Login to Element Android
3. Verify through cross signing
4. Try to recover encrypted messages through Key Backup.
5. I get promted to enter my passphrase / Security key

### Outcome

#### What did you expect?
Key Backup works without me needing to enter my passphrase / Recovery key.

#### What happened instead?
I have to enter my Passphrase / Recovery Key after cross signing to get access to my key backup.

### Your phone model

Pixel 6

### Operating system version

Android 13

### Application version and app store

Element Android 1.5.32

### Homeserver

Synapse 1.82.0

### Will you send logs?

Yes

### Are you willing to provide a PR?

Yes