fingerprint: remove metadata from digitalocean

[kevinschoonover]

follow up to #12028.

Feel free to close this as noise as I'm not sure if this PR is necessary, but wanted to try to address the comments on #12028 since metadata was a remanent of me copying the GCE fingerprinter and is not necessary / used.

ran the tests locally:

 > pwd
./nomad/client/fingerprint
> go test
PASS
ok  	github.com/hashicorp/nomad/client/fingerprint	0.875s

[tgross]

This LGTM and thanks for following up.

I'm not sure why CircleCI isn't running for your PRs. It does for other non-HashiCorp contributors (ex #12021) and as far as I can tell there's nothing in the workflows that should be excluding you, so that's weird. But that's on us to figure out 😀

[github-actions]

I'm going to lock this pull request because it has been closed for 120 days ⏳. This helps our maintainers find and focus on the active contributions.
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