improve benchmarking error output (#7863)

* add concat Vec<u8> function and use it for better error logging in add_benchmark! macro

* refactor benchmark error reporting to use format! and RuntimeString

substrate/utils/frame/benchmarking-cli/src/command.rs

@@ -174,7 +174,7 @@ impl BenchmarkCmd {
 					}
 				}
 			},
-			Err(error) => eprintln!("Error: {:?}", error),
+			Err(error) => eprintln!("Error: {}", error),
 		}
 
 		Ok(())