Bump third_party/ot-br-posix/repo from `bd15f71` to `722f283` #5569

Job	Run time
Build on Linux (fake, gcc_release, clang, simulated)	55m 6s
Build on Linux (gcc_debug)	1h 3m 46s
Build on Linux (python_lib)	22m 33s
Build on Darwin (clang, simulated)	51m 22s
Build on Linux (coverage)	14m 31s
Build on Linux (python lighting-app)	5m 43s
	3h 33m 1s

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