Disable debug info by default in `dev` profile

I've had this as a local override for a while on my machine, but https://github.com/apache/datafusion/pull/17677 just reminded me about it.

Should we disable debug info (`debug = false`) by default in the `dev` profile? It significantly speeds up incremental builds.

Helpful context: https://kobzol.github.io/rust/rustc/2025/05/20/disable-debuginfo-to-improve-rust-compile-times.html

Start by locating the repository configuration for the Rust `dev` profile and inspect how `debug` is currently set. Change the default to `debug = false`, then verify that the profile still works and that incremental builds use the updated setting.

Written by the indexing model from the issue text.