BlobBackupDatasourceParameters objectType is missing from BackupInstance policy parameters

### Resource Type

Microsoft.DataProtection/backupVaults/backupInstances

### Api Version

2025-07-01

### Issue Type

Type is unavailable

### Other Notes

I tried to create a backup instance for our blob storage and then filter the blob containers using BlobBackupDatasourceParameters based on [this](https://learn.microsoft.com/en-us/azure/backup/backup-blobs-storage-account-arm-template) document.
In the latest version of bicep (0.37.4), the only availabe values for `policyInfo.policyParametersbackupDatasourceParametersList.objectType` are `AdlsBlobBackupDatasourceParameters` and `KubernetesClusterBackupDatasourceParameters` and it misses the `BlobBackupDatasourceParameters` value to filter blob containers in the backup.

### Bicep Repro

resource backupInstance 'Microsoft.DataProtection/backupVaults/backupInstances@2025-07-01' = {
name: backupInstanceName
parent: backupVault
properties: {
dataSourceInfo: {
resourceID: storageAccountId
objectType: 'Datasource'
resourceLocation: location
datasourceType: 'Microsoft.Storage/storageAccounts/blobServices'
}
objectType: 'BackupInstance'
policyInfo: {
policyId: backupPolicyId
policyParameters: {
backupDatasourceParametersList: [
{
containersList: blobContainersList
objectType: 'BlobBackupDatasourceParameters'
}
]
}
}
}
}

### Confirm

- [x] I have read the troubleshooting guide and looked for duplicates.

Start in the bicep-types-az type definitions for Microsoft.DataProtection/backupVaults/backupInstances at API version 2025-07-01 and locate the policyParameters backupDatasourceParametersList objectType declaration. Compare it with the documented BlobBackupDatasourceParameters value and the existing AdlsBlobBackupDatasourceParameters and KubernetesClusterBackupDatasourceParameters values. Done means the Bicep repro accepts BlobBackupDatasourceParameters for filtering blob containers.

Written by the indexing model from the issue text.