AKS: Unable to upgrade Nodepool's k8s version

[github-actions]

This is a forwardport issue for #12860, automatically created via GitHub Actions workflow initiated by @richard-cox

Original issue body:

Setup
Rancher: v2.9-eaafb03a1ed78475258b7523b514168a8d9c8367-head
Dashboard: release-2.9 c2c221a

Describe the bug
Unable to upgrade Nodepool kubernetes version. "A new cluster version has been selected. Once the upgrade has completed, you can come back and upgrade the node pool version" warning is not getting cleared.

To Reproduce

• Provision AKS cluster from Rancher UI
• Upgrade control plane version to new one, valid warning is displayed for Nodepool
• Once the upgrade is finished, edit cluster and try upgrading Nodepool

Screenshots

2.9-head:

2.9.3 (as expected):

[izaac]

Rancher version: v2.11-d224815d7cfbf4194db1ffdfb04676d55d1a2062-head
UI version: release-2.10 5218335

The same scenarios from 2.10 were executed to validate the fix in this version 2.11

I used an AKS hosted cluster with multiple node pools.
Selecting a newer k8s version shows the info box as expected regarding the pools update option after update.
If I select the current version back, the info box is hidden as expected.

I did two version bumps:

• Update Kubernetes version. Save
• Wait until the checkbox is visible in the Edit view.
• Checked that multiple nodepools have this checkbox visible.
• Update Pool A and save. Wait for update.
• Go to edit again after waiting for the upgrade, Pool A is upgraded to the current kubernetes version. The checkbox is hidden.
• Navigating to Pool B which is still not upgraded has the upgrade checkbox visible and information about the upgrade to version.
• Check the box save and wait for Pool B to be upgraded.
• All the pools match the kubernetes versions after the upgrade and going to edit.
• Previous versions before the current in the Kubernetes versions dropdown are hidden

---

• Next Scenario, version bump, repeat the above.

Closing as validated.