[aks-preview@20.0.0b8] az aks update: "ValueError: too many values to unpack (expected 3)"

### Describe the bug

` az aks update ` will result error with aks-preview@20.0.0b8

### Related command

Run `az aks update --name "my-cluster-1" --resource-group "my-rg-1" --tags test_label=2`
or run `az aks update `

### Errors

```
The behavior of this command has been altered by the following extension: aks-preview
The command failed with an unexpected error. Here is the traceback:
too many values to unpack (expected 3)
Traceback (most recent call last):
File "/lib64/az/lib/python3.12/site-packages/knack/cli.py", line 233, in invoke
cmd_result = self.invocation.execute(args)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/lib64/az/lib/python3.12/site-packages/azure/cli/core/commands/__init__.py", line 666, in execute
raise ex
File "/lib64/az/lib/python3.12/site-packages/azure/cli/core/commands/__init__.py", line 734, in _run_jobs_serially
results.append(self._run_job(expanded_arg, cmd_copy))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/lib64/az/lib/python3.12/site-packages/azure/cli/core/commands/__init__.py", line 703, in _run_job
result = cmd_copy(params)
^^^^^^^^^^^^^^^^
File "/lib64/az/lib/python3.12/site-packages/azure/cli/core/commands/__init__.py", line 336, in __call__
return self.handler(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/lib64/az/lib/python3.12/site-packages/azure/cli/core/commands/command_operation.py", line 120, in handler
return op(**command_args)
^^^^^^^^^^^^^^^^^^
File "/home/user/.azure/cliextensions/aks-preview/azext_aks_preview/custom.py", line 1459, in aks_update
mc = aks_update_decorator.update_mc_profile_preview()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/user/.azure/cliextensions/aks-preview/azext_aks_preview/managed_cluster_decorator.py", line 8099, in update_mc_profile_preview
mc = self.update_mc_profile_default()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/lib64/az/lib/python3.12/site-packages/azure/cli/command_modules/acs/managed_cluster_decorator.py", line 9501, in update_mc_profile_default
mc = self.update_network_profile_advanced_networking(mc)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/lib64/az/lib/python3.12/site-packages/azure/cli/command_modules/acs/managed_cluster_decorator.py", line 8210, in update_network_profile_advanced_networking
(acns_enabled, acns_observability, acns_security) = self.context.get_acns_enablement()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: too many values to unpack (expected 3)
```

### Issue script & Debug output

N/A

### Expected behavior

No error

### Environment Summary

```
> az -v
azure-cli 2.81.0 *

core 2.81.0 *
telemetry 1.1.0

Extensions:
aks-preview 20.0.0b8

Dependencies:
msal 1.34.0b1
azure-mgmt-resource 23.3.0
```

### Additional context

_No response_