Bump third_party/ot-br-posix/repo from `bd15f71` to `9ca3b36` #393

Job	Run time
REPL Tests - Darwin	0s
REPL Tests - Linux	1h 33m 40s
Test Suites - Darwin (no-ble-no-shell-asan-clang)	1h 36m 40s
Test Suites - Linux (no-ble-no-shell-tsan-clang)	2h 1m 44s
Test Suites - Darwin (no-ble-no-shell-tsan-clang)	2h 15m 17s
	7h 27m 21s

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