Bump third_party/openthread/repo from `287dbfa` to `0fb1c22` #422

Job	Run time
Build on Darwin (clang, simulated)	1h 5m 4s
Build on Linux (fake, gcc_release, clang, simulated)	51m 30s
Build on Linux (coverage)	13m 5s
Build on Linux (gcc_debug)	1h 2m 53s
Build on Linux (python_lib)	23m 53s
Build on Linux (python lighting-app)	7m 30s
	3h 43m 55s

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