[AVM Module Issue]: Update the default of the `zones` param in Bastion Host

### Check for previous/existing GitHub issues

- [x] I have checked for previous/existing GitHub issues

### Issue Type?

Feature Request

### Module Name

avm/res/network/bastion-host

### (Optional) Module Version

_No response_

### Description

As per https://learn.microsoft.com/en-us/azure/bastion/configuration-settings, the availability zones support in Azure Bastion Host is currently in preview and not available in all regions, therefore the default value for the `zones` parameter is an empty array.

One the availability zones are generally available, the default value of the `zones` parameter should be set to [1, 2, 3]. This issue is intended to track this activity.

### (Optional) Correlation Id

_No response_