Promote storageRedundancy to Stable API Version for azurerm_mysql_flexible_server

### API Spec link

https://github.com/Azure/azure-rest-api-specs/blob/main/specification/mysql/resource-manager/Microsoft.DBforMySQL/FlexibleServers/preview/2024-10-01-preview/FlexibleServers.json#L1008

### API Spec version

2024-10-01-preview

### Question/Query

Hi Team,

Regarding the azurerm_mysql_flexible_server resource, the REST API support for the storageRedundancy property is currently still in Preview. As a result, the Terraform AzureRM provider does not currently support the storageRedundancy option.

The related Terraform issue is: https://github.com/issues/created?issue=hashicorp%7Cterraform-provider-azurerm%7C30511&issue_global_id=I_kwDOBZHfms7I1QXe

Could this property be considered for promotion from Preview to Stable so that it can be supported natively by Terraform?

At the moment, we have to use both the azurerm and azapi providers within our modules to enable storageRedundancy. This adds unnecessary complexity and makes the Terraform configuration more difficult to maintain.

Would it be possible to prioritize this request and consider moving the property to the stable API version?

Thanks for your consideration.

### Environment

_No response_

Start by reviewing the linked FlexibleServers.json API specification at the storageRedundancy property and compare its 2024-10-01-preview status with the stable API version. Done means the property is promoted to a stable API version so the related Terraform AzureRM issue can support it without requiring azapi.

Written by the indexing model from the issue text.