Remove `abort_on_panic()` since Rust 1.81?

[MarijnS95]

In #412 @spencercw neatly added a wrapper to catch panics instead of unsoundly unwinding them across an extern "C" boundary. Rust 1.81 now plugged that hole and always aborts already:

https://blog.rust-lang.org/2024/09/05/Rust-1.81.0.html#abort-on-uncaught-panics-in-extern-c-functions

This should allow us to get rid of the manual catch+abort when our MSRV is 1.81. Unsure if that gets propagated in the same detail to stderr / Android logs though.