[BUG] Backup Vault Delete API returns when the resource isn't fully deleted

### API Spec link

https://github.com/Azure/azure-rest-api-specs/blob/e96c24570a484cff13d153fb472f812878866a39/specification/dataprotection/resource-manager/Microsoft.DataProtection/DataProtection/stable/2024-04-01/dataprotection.json#L383

### API Spec version

2024-04-01

### Describe the bug

Backup Vault Delete API returns when the resource isn't fully deleted.

### Expected behavior

Backup Vault Delete API returns when the resource is fully deleted

### Actual behavior

Backup Vault Delete API returns when the resource isn't fully deleted.

### Reproduction Steps

1. Create Resource group
2. Create Backup Vault
3. Invoke Backup Vault Delete API to delete Backup Vault but API returns before the resource is fully deleted.

### Environment

PROD

Start with the dataprotection.json API definition at line 383 and read the surrounding Backup Vault delete operation. Compare its response behavior with nearby DataProtection definitions and the repository's available validation checks. Done means the specification accurately represents completion only after the Backup Vault is fully deleted.

Written by the indexing model from the issue text.