Bump third_party/openthread/repo from cf357d7 to b212a0a (project…

…-chip#32067)

Bumps [third_party/openthread/repo](https://github.com/openthread/openthread) from `cf357d7` to `b212a0a`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@cf357d7...b212a0a)

---
updated-dependencies:
- dependency-name: third_party/openthread/repo
  dependency-type: direct:production
...

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