Fix warnings for Rust 1.84.1

```
error: needless call to `as_bytes()`
   --> frameworks/native/libs/binder/rust/src/parcel/parcelable.rs:610:21
    |
610 | s.as_bytes().len().try_into().or(Err(StatusCode::BAD_VALUE))?,
    |                     ^^^^^^^^^^^^^^^^^^ help: `len()` can be called directly on strings: `s.len()`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_as_bytes
    = note: `-D clippy::needless-as-bytes` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::needless_as_bytes)]`
```

Bug: http://b/394897447
Test: m
Flag: EXEMPT refactor

Change-Id: Ifd4034cacd680fff7d78efeba4cf05913574d031
1 file changed