fix: dedupe SMDClient.refreshLock and InterfaceManager.GetPublicKey()

[synackd]

Description

These were somehow duplicated in recent PRs, causing several checks on main to fail. They are deduplicated in this PR.

Fixes failing checks on main.

Checklist

• My code follows the style guidelines of this project
• I have added/updated comments where needed
• I have added tests that prove my fix is effective or my feature works
• I have run make test (or equivalent) locally and all tests pass
• I have updated the relevant documentation (CLI examples, man pages, README, other docs, etc.)
• DCO Sign-off: All commits are signed off (git commit -s) with my real name and email
• REUSE Compliance:
  • Each new/modified source file has SPDX copyright and license headers
  • Any non-commentable files include a <filename>.license sidecar
  • All referenced licenses are present in the LICENSES/ directory

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update
• Dependency update
• Build system/CI

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• I agree to follow the Code of Conduct.