Remove all deprecated variables in `v10`.

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Description

We should remove all variables in `deprecated_variables.tf` file before we release `v10`.

### New or Affected Resource(s)/Data Source(s)

azurerm_kubernetes_cluster

### Potential Terraform Configuration

```hcl

```

### References

_No response_