Improve tracing (#5698)

* Improve tracing implementation

* Enable tracing in runtime interfaces

* Switch to `TRACE` level

substrate/primitives/runtime-interface/src/lib.rs

@@ -109,6 +109,9 @@ extern crate self as sp_runtime_interface;
 #[cfg(feature = "std")]
 pub use sp_wasm_interface;
 
+#[doc(hidden)]
+pub use sp_tracing;
+
 #[doc(hidden)]
 pub use sp_std;