[release-1.28] Make /db/info available anonymously from localhost

[brandond]

Proposed Changes

• Backport https://github.com/k3s-io/k3s/pull/10001

The Rancher CAPR planner apparently queries this anonymously to get the IP address of the first etcd node (to be used as the init node), instead of just using the address of the first node with the etcd label.

• https://github.com/rancher/rancher/blob/3a426b5ba059358f8874573c0a98d01bfda25a47/pkg/capr/planner/instructions.go#L105-L106
• https://github.com/rancher/rancher/blob/3a426b5ba059358f8874573c0a98d01bfda25a47/pkg/capr/planner/store.go#L612-L624

K3s itself uses auth when retrieving this resource, but since Rancher does not we need to make it available anonymously again - at least from localhost.

Types of Changes

integration/ bugfix

Verification

• curl -ks https://localhost:6443/db/info on an etcd node.
• Build a split-role cluster from Rancher, confirm all the nodes join properly.

Testing

Linked Issues

• https://github.com/k3s-io/k3s/issues/10007

  User-Facing Change

Further Comments

[brandond]

virtualbox image for btrfs test appears to be broken, and arm flaked. merging