Bump third_party/openthread/repo from `ba826ff` to `4a7c447` (#23652)

Bumps [third_party/openthread/repo](https://github.com/openthread/openthread) from `ba826ff` to `4a7c447`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](https://github.com/openthread/openthread/compare/ba826ffb2ac7e2d366ebd553b92a912434ff603d...4a7c447f6c381ee6f695371c8b20dcc2be895211)

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

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Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
diff --git a/third_party/openthread/repo b/third_party/openthread/repo
index ba826ff..4a7c447 160000
--- a/third_party/openthread/repo
+++ b/third_party/openthread/repo
@@ -1 +1 @@
-Subproject commit ba826ffb2ac7e2d366ebd553b92a912434ff603d
+Subproject commit 4a7c447f6c381ee6f695371c8b20dcc2be895211