Remove extern crate tracing from numerous crates.

compiler/rustc_errors/src/translation.rs

@@ -6,6 +6,7 @@ pub use rustc_error_messages::FluentArgs;
 use std::borrow::Cow;
 use std::env;
 use std::error::Report;
+use tracing::{debug, trace};
 
 /// Convert diagnostic arguments (a rustc internal type that exists to implement
 /// `Encodable`/`Decodable`) into `FluentArgs` which is necessary to perform translation.