[release-1.28] Bump K3s version for v1.28

[brandond]

Proposed Changes

Updates k3s: k3s-io/k3s@4c1b91e...c15e176

Types of Changes

k3s bump

Verification

Check k3s version

Testing

Linked Issues

• [Release-1.28] - rke2-server creates improper etcd member name #5598
• [Release-1.28] - Duplicate endpoints prevents any endpoint from being used #5601

User-Facing Change

fix: use correct wasm shims names
Bump spegel to v0.0.18-k3s3
Adds wildcard registry support
Fixes issue with excessive CPU utilization while waiting for containerd to start
Add env var to allow spegel mirroring of latest tag
Bump helm-controller/klipper-helm versions
Fix snapshot prune
Fix issue with etcd node name missing hostname
Fix additional corner cases in registries handling
RKE2 will now warn and suppress duplicate entries in the mirror endpoint list for a registry. Containerd does not support listing the same endpoint multiple times as a mirror for a single upstream registry.

Further Comments