remove --all-features from test_rust.sh
After #26399 (moved), none of our crates will have any features. However, we'd like to feature-gate testing C code from Rust (#26398 (moved)) as a temporary workaround to #25386 (moved), so we need to remove the
--all-features flag. The
--all-features flags was probably a bad idea to begin with, as many crates have mutually incompatible features (e.g.
curve25519-dalek has features for different field implementation backends).