Use debug log level for developer oriented logs

The information logged here is of limited general interest, while at the
same times makes it impractical to simply enable logging and share the
resulting logs due to the amount of the output produced.

Reduce log level from info to debug for developer oriented information.

For example, when building cargo, this reduces the amount of logs
generated by `RUSTC_LOG=info cargo build` from 265 MB to 79 MB.

Continuation of changes from 81350.

compiler/rustc_trait_selection/src/traits/codegen.rs

@@ -91,7 +91,7 @@ pub fn codegen_fulfill_obligation<'tcx>(
         });
         let impl_source = drain_fulfillment_cx_or_panic(&infcx, &mut fulfill_cx, impl_source);
 
-        info!("Cache miss: {:?} => {:?}", trait_ref, impl_source);
+        debug!("Cache miss: {:?} => {:?}", trait_ref, impl_source);
         Ok(impl_source)
     })
 }