[backport v2.8.next1] Add warning banner to allocate the number of nodes + 1 vGPUs

[github-actions]

This is a backport issue for #10989, automatically created via GitHub Actions workflow initiated by @gaktive

Original issue body:

Setup
Rancher version:v2.8-head
Browser type & version: Chrome Version 124.0.6367.78
Harvester Version: v1.3.0

To Reproduce

1. Set up vGPU profiles (multiple) in Harvester
2. Import Harvester into Rancher
3. Go to Virtualization management -> Harvester UI for cluster -> vGPU Devices and enable a vGPU with 2 allocatable.
4. From Cluster Management, Create a new 2-node RKE2 cluster with Harvester as the downstream provider. Under Advanced options, add the vGPU with 2 allocatable resources ( same number as the cluster nodes)
5. After the creation of the cluster is completed, edit the config file of the cluster
6. Observe the logs of the failed process of provisioning.

Result
Once the harvester cluster is redeployed for any reason (the user edits the config, the nodes go into an error state, etc), the new VMs spin up before the old ones are completely shut down, which causes the "un-schedulable" error as the vGPUs won't be available yet.

Expected Result
We could add a warning banner in the UI to recommend that the user should provision N+1 allocatable vgpu, where N is number of nodes.

[nwmac]

@torchiaf based on this comment #11017 (comment) - I assume the same is true here - and that we should push this to 2.8.next2 - can you confirm?

[torchiaf]

@torchiaf based on this comment #11017 (comment) - I assume the same is true here - and that we should push this to 2.8.next2 - can you confirm?

@nwmac confirmed.

[nwmac]

FYI @gaktive

[gaktive]

This may be unblocked by Harvester now. @torchiaf check if that's the case since we need to include the warning in this release too. @ibrokethecloud can get an env up upon request to help.