feat: bump RKE2 to v1.28.12+rke2r1 and Rancher to v2.8.5 (backport #787)

[mergify]

Solution:

Bump RKE2 to v1.28.12+rke2r1 and Rancher to v2.8.5.

Related Issue:
harvester/harvester#6262

Test plan:

1. Create harvester in airgap environment and make sure all pod can up.
2. Check basic VM operation can work.

---

This is an automatic backport of pull request #787 done by [Mergify](https://mergify.com).

[mergify]

Cherry-pick of d125b5d has failed:

On branch mergify/bp/v1.3/pr-787
Your branch is up to date with 'origin/v1.3'.

You are currently cherry-picking commit d125b5d.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   package/harvester-os/files/usr/share/rancher/rancherd/config.yaml.d/50-defaults.yaml
	modified:   scripts/images/rancherd-bootstrap-images.txt
	modified:   scripts/version-rancher
	modified:   scripts/version-rke2

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   scripts/images/rancher-images.txt

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[FrankYang0529]

LGTM. I can install this PR in airgap environment without error.

[w13915984028]

Those 2 images happend to be updated, they are related to rancher-monitoring stack not Rancher.

docker.io/rancher/mirrored-prometheus-prometheus:v2.45.0
docker.io/rancher/mirrored-prometheus-alertmanager:v0.26.0