Bump third_party/mbedtls/repo from `06c466d` to `b53e630` #1519

Job	Run time
REPL Tests - Linux	37m 36s
REPL Tests - Darwin	0s
Test Suites - Linux (no-ble-tsan-clang)	1h 51m 23s
Test Suites - Darwin (no-ble-asan-clang)	1h 37m 12s
Test Suites - Darwin (no-ble-tsan-clang)	2h 3m 8s
	6h 9m 19s

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