Using Containerfile shouldn't output warning

[nakamorichi]

@manugupt1 Why does this raise warning? I don't think using Containerfile when Dockerfile doesn't exist should output warning.

Originally posted by @Kitanotori in https://github.com/containerd/nerdctl/pull/1219#discussion_r937313898

[manugupt1]

I think we should log and let users know users with log.Info not log.Warn. We should not removing logging though as it is nerdctl specific behavior.

[nakamorichi]

There's already log for => [internal] load build definition from Containerfile, so the mentioned log is unnecessary.

[manugupt1]

This is fixed. Can we close this now