Bump third_party/perfetto/repo from `b9aca8f` to `6f9824f` #351

Job	Run time
REPL Tests - Darwin	0s
REPL Tests - Linux	2m 2s
Test Suites - Darwin (no-ble-asan-clang)	1h 28m 8s
Test Suites - Linux (no-ble-tsan-clang)	1m 46s
Test Suites - Darwin (no-ble-tsan-clang)	2h 1m 51s
	3h 33m 47s

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