Something in C2Rust mistranspiles around LED_PORT; disabling the board for all Rust examples/tests.
This pulls in adjustments to the C-nonbreaking but Rust-breaking API change in https://github.com/RIOT-OS/RIOT/pull/17359 cstr_core is forcibly kept at 0.2.4 because 0.2.5 needs a newer nightly than riotdocker currently has.