rust: pin-init: examples: pthread_mutex: disable the main test for miri
`miri` takes a long time to execute the test, so disable it.
Link: https://github.com/Rust-for-Linux/pin-init/pull/50/commits/e717a9eec85024c11e79e8bd9dcb664ad0de8f94
Link: https://lore.kernel.org/all/20250523125424.192843-3-lossin@kernel.org
Signed-off-by: Benno Lossin <lossin@kernel.org>
authored by