[Enhancement]: Allow users to select the cloud provider while deploying a new private bench.

### Affected Area

None

### Problem Statement

Ref https://support.frappe.io/helpdesk/tickets/62779?view=VIEW-HD+Ticket-010
When creating a new private bench, users can only see the region but not the cloud provider, which can be a bit confusing for them.

If the option to select the cloud provider is provided during private bench creation, it would be better than asking for it after the bench has been deployed and a new site has been created.

### Proposed Solution

_No response_

Start by tracing the private bench creation flow and the point where users currently choose a region. Determine how the cloud provider is represented and where provider selection must occur before deployment; done means users can choose a provider during private bench creation rather than afterward.

Written by the indexing model from the issue text.