Bump third_party/openthread/repo from eaa2779 to b200c96 (#26565)

Bumps [third_party/openthread/repo](https://github.com/openthread/openthread) from `eaa2779` to `b200c96`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](openthread/openthread@eaa2779...b200c96)

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

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