Bump third_party/mbedtls/repo from `da635ab` to `04a8d02` #1116

Job	Run time
Build on Linux (fake, gcc_release, clang, simulated)	1h 15m 50s
Build on Linux (gcc_debug)	35m 9s
Build on Linux (python_lib)	17m 46s
Build on Linux (python lighting-app)	6m 30s
Build on Darwin (clang, python_lib, simulated)	33m 36s
Build on Linux (coverage)	9m 11s
	2h 58m 2s

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