Bump third_party/ot-br-posix/repo from `ff2f24c` to `03132d3` #1355

Job	Run time
Unit / Integration Tests (main)	12m 43s
Unit / Integration Tests (clang)	12m 4s
Unit / Integration Tests (mbedtls)	13m 33s
Unit / Integration Tests (rotating_device_id)	14m 18s
	52m 38s

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