Bump third_party/openthread/repo from `aed9cd1` to `147de7e` #1972

Job	Run time
Unit / Integration Tests (main)	16m 19s
Unit / Integration Tests (clang)	17m 1s
Unit / Integration Tests (mbedtls)	16m 4s
Unit / Integration Tests (rotating_device_id)	17m 37s
Unit / Integration Tests (icd)	46m 22s
	1h 53m 23s

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