Bump third_party/pigweed/repo from `1f12d06` to `269b600` #2308

Job	Run time
Build on Darwin (clang, python_lib, simulated)	2m 57s
Build on Linux (fake, gcc_release, clang, simulated)	1h 49m 47s
Build on Linux (gcc_debug)	1h 19m 40s
Build on Linux (coverage)	21m 24s
Build on Linux (python_lib)	2m 2s
Build on Linux (python lighting-app)	1m 42s
	3h 37m 32s

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