Do not use the NS peer as a label

[adriansmares]

Summary

This PR reduces the cardinality of two AS metrics which use the NS peer as the label. The peer name is not relevant and inconsistent (it mixes peer address with peer name).

Changes

• Remove the network_server label for the received uplinks and forwarded downlinks.

Testing

🐒

Regressions

We do not use these labels in our aggregations, so there shouldn't be any regressions.

Checklist

• Scope: The referenced issue is addressed, there are no unrelated changes.
• Compatibility: The changes are backwards compatible with existing API, storage, configuration and CLI, according to the compatibility commitments in README.md for the chosen target branch.
• Documentation: Relevant documentation is added or updated.
• Changelog: Significant features, behavior changes, deprecations and fixes are added to CHANGELOG.md.
• Commits: Commit messages follow guidelines in CONTRIBUTING.md, there are no fixup commits left.