Bump third_party/openthread/repo from `faeea3d` to `e66c21c` (#23774)

Bumps [third_party/openthread/repo](https://github.com/openthread/openthread) from `faeea3d` to `e66c21c`.
- [Release notes](https://github.com/openthread/openthread/releases)
- [Commits](https://github.com/openthread/openthread/compare/faeea3d2b9df48dd769592b7c5a85609c0c48389...e66c21c3dafa73577035102f1d224d550134f42d)

---
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 faeea3d..e66c21c 160000
--- a/third_party/openthread/repo
+++ b/third_party/openthread/repo
@@ -1 +1 @@
-Subproject commit faeea3d2b9df48dd769592b7c5a85609c0c48389
+Subproject commit e66c21c3dafa73577035102f1d224d550134f42d