helm: Do not suggest enabling macspoofchk
NOTE this option was not in the buildkitd referenced configuration. I added it after reading the CNI reference but didn't realize it required an additional nft binary to be present.
failed to setup spoof-check: failed to execute nft nft -j -f /tmp/spoofcheck-3647386428: exec: "nft": executable file not found in $PATH
Bug: T329213