default debug level

[zahash]

in crates/youki/src/observability.rs there is this line

/// If not in debug mode, default level is warn to get important logs
#[cfg(not(debug_assertions))]
const DEFAULT_LOG_LEVEL: &str = "error";

it says the default level is warn but it is set to error.

should the comment be changed?

[zahash]

in any case, here is a PR #2737