Fix incorrect hostname on non-managed devices

[Gold856]

Description

I have all sorts of weird adapters from npcap and Hyper-V that don't have MAC addresses, so I'm simplifying the logic down so that it always tries to find any adapter with a MAC address, but attempts to see if it can find what adapter is in use right now and use the MAC address from that. This also unpublishes old MAC address topics and also will publish a default MAC address so the topics don't just spill out into the root photonvision table.

Meta

Merge checklist:

• Pull Request title is short, imperative summary of proposed changes
• The description documents the what and why
• This PR has been linted.
• If this PR changes behavior or adds a feature, user documentation is updated
• If this PR touches photon-serde, all messages have been regenerated and hashes have not changed unexpectedly
• If this PR touches configuration, this is backwards compatible with settings back to v2025.3.2
• If this PR touches pipeline settings or anything related to data exchange, the frontend typing is updated
• If this PR addresses a bug, a regression test for it is added