submodule: bump third_party/openthread/repo from `0833468` to `4ff5ab6` (#858)
submodule: bump third_party/openthread/repo from `0833468` to `4ff5ab6` (#858)

Bumps [third_party/openthread/repo](https://github.com/openthread/openthread) from `0833468` to `4ff5ab6`.
- [Commits](https://github.com/openthread/openthread/compare/08334687679417514ff245b58f10cca73692b0cb...4ff5ab67d7cd6a6cbd28d55ed4e244fb9c3b8833)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@github.com>

Co-authored-by: dependabot[bot] <1c358da00a777d4e9898c1280ab801e2df165188@users.noreply.github.com>
openthread/ot-br-posix,openthread/ot-br-posix,openthread/ot-br-posix,openthread/borderrouter,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter,openthread/borderrouter,openthread/ot-br-posix,openthread/borderrouter,openthread/borderrouter,openthread/ot-br-posix