[AVM Module Issue]: Azure Stack HCI Network Interface enters Failed provisioning state due to attempted MAC address update during redeployment

### Check for previous/existing GitHub issues

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

### Issue Type?

Bug

### Module Name

avm/res/azure-stack-hci/network-interface

### (Optional) Module Version

_No response_

### Description

An existing Azure Local (Azure Stack HCI) Network Interface resource unexpectedly moved to a `Failed` provisioning state after the deployment pipeline had not run for an extended period.

The 2026-06-23 Azure DevOps pipeline failed with the following error:
```
{
"details": [
{
"code": "InternalError",
"message": "admission webhook \"createupdatevalidationwebhook.infrastructure.azstackhci.microsoft.com\" denied the request: Blocked NetworkInterface Update : MAC Address cannot be changed after resource creation"
}
]
}
```
The associated Network Interface resource was found to be in a `Failed` provisioning state:
```
{
"type": "microsoft.azurestackhci/networkinterfaces",
"provisioningState": "Failed",
"systemData": {
"createdAt": "2026-04-02T17:23:51.3610066Z",
"lastModifiedAt": "2026-06-23T11:52:14.655285Z"
}
}
```
The `avm/res/azure-stack-hci/network-interface` module is used to deploy the NIC, and the `avm/res/azure-stack-hci/virtual-machine-instance` module attaches it to the VM:
```
module hciVirtualMachine_nic 'br/public:avm/res/azure-stack-hci/network-interface:0.1.1' = {
params: {
name: '${vmName}-NIC'
customLocationResourceId: hciCustomLocationResourceId
ipConfigurations: [
{
name: '${vmName}-nic'
properties: {
subnet: {
id: hciLogicalNetworkId
}
}
}
]
}
}

module hciVirtualMachine 'br/public:avm/res/azure-stack-hci/virtual-machine-instance:0.1.2' = {
params: {
networkProfile: {
networkInterfaces: [
{
id: hciVirtualMachine_nic.outputs.resourceId
}
]
}
}
}
```

### (Optional) Correlation Id

_No response_