[BUG] Rancher Prime cluster cleanup job has wrong image

[m-ildefons]

Rancher Server Setup

• Rancher version: v2.7.12 (prime)
• Installation option (Docker install/Helm Chart): vcluster / helm

Information about the Cluster

• Kubernetes version: v1.27.12-k3s1
• Cluster Type (Local/Downstream): vcluster
  • If downstream, what type of cluster? (Custom/Imported or specify provider for Hosted/Infrastructure Provider): Imported

User Information

• What is the role of the user logged in? (Admin/Cluster Owner/Cluster Member/Project Owner/Project Member/Custom)
  • If custom, define the set of permissions: admin

Describe the bug
When unregistering a Harvester cluster from a prime-only Rancher instance, the Rancher agent's cleanup job is deployed with the wrong image:

 ErrImagePull (rpc error: code = NotFound desc = failed to pull and unpack image "docker.io/rancher/rancher-agent:v2.7.12": failed to resolve reference "docker.io/rancher/rancher-agent:v2.7.12": docker.io/rancher/rancher-agent:v2.7.12: not found) 

To Reproduce

1. Install a Harvester cluster
2. Install a prime-only Rancher instance (e.g. v2.7.12)
3. Import the Harvester cluster to the Rancher instance
4. Unset the cluster-registration-url setting of the Harvester cluster

Result
The Rancher agent will spawn a cleanup job with the wrong image. This job's Pod ends up in an image pull backoff state because the configured image does not exist on the registry.

Expected Result
The cleanup job should be spawned with the correct image and succeed.

Screenshots

Additional context

rancher/pkg/agent/clean/node_notwindows.go

Line 235 in 8298de0

agentImage = "rancher/rancher-agent:master"