Bump k3s-root to v0.15.0

[brandond]

Proposed Changes

• Bump k3s-root to v0.15.0
• Bump kine to fix metrics panic with --kine-tls introduced in Wire up kine metrics #12831

Types of Changes

version bump

Verification

• See linked issue
• Check nft version/json support:

root@k3s-server-001:~# nft --version
nftables v1.1.0 (Commodore Bullmoose)

root@k3s-server-001:~# nft --json list tables
{"nftables": [{"metainfo": {"version": "1.1.0", "release_name": "Commodore Bullmoose", "json_schema_version": 1}}, {"table": {"family": "ip", "name": "mangle", "handle": 1}}, {"table": {"family": "ip6", "name": "mangle", "handle": 3}}, {"table": {"family": "ip", "name": "nat", "handle": 4}}, {"table": {"family": "ip6", "name": "nat", "handle": 5}}, {"table": {"family": "ip6", "name": "filter", "handle": 6}}, {"table": {"family": "ip", "name": "kube-proxy", "handle": 9, "comment": "rules for kube-proxy"}}, {"table": {"family": "ip6", "name": "kube-proxy", "handle": 10, "comment": "rules for kube-proxy"}}, {"table": {"family": "ip", "name": "filter", "handle": 21}}]}

Testing

yes

Linked Issues

• Bump k3s-root for nft json support #12852

User-Facing Change

The bundled userspace binaries are now built from the buildroot 2025.02 LTS branch.
The bundled nft binary now supports json output, required for compatibility with kube-proxy's nft proxier.

Further Comments

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 20.45%. Comparing base (d08bf6c) to head (7073ab9).
⚠️ Report is 3 commits behind head on master.

❗ There is a different number of reports uploaded between BASE (d08bf6c) and HEAD (7073ab9). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (d08bf6c)	HEAD (7073ab9)
e2etests	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##           master   #12853       +/-   ##
===========================================
- Coverage   40.57%   20.45%   -20.12%     
===========================================
  Files         185      182        -3     
  Lines       18931    18865       -66     
===========================================
- Hits         7681     3859     -3822     
- Misses      10069    14570     +4501     
+ Partials     1181      436      -745     

Flag	Coverage Δ
e2etests	?
unittests	20.45% <100.00%> (+0.01%)	⬆️

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