Bump third_party/perfetto/repo from `b9aca8f` to `8a2b235` #5554

Job	Run time
Build on Darwin (clang, simulated)	8m 42s
Build on Linux (fake, gcc_release, clang, simulated)	3m 1s
Build on Linux (gcc_debug)	2m 25s
Build on Linux (coverage)	14m 29s
Build on Linux (python_lib)	3m 9s
Build on Linux (python lighting-app)	5m 50s
	37m 36s

Provide feedback