Minor tweaks suggested by clippy (#10673)

* Minor tweaks suggested by clippy

* Fix typo caused by last commit

* Apply review suggestions

substrate/primitives/api/proc-macro/src/decl_runtime_apis.rs

@@ -378,6 +378,7 @@ fn generate_call_api_at_calls(decl: &ItemTrait) -> Result<TokenStream> {
 		// Generate the generator function
 		result.push(quote!(
 			#[cfg(any(feature = "std", test))]
+			#[allow(clippy::too_many_arguments)]
 			pub fn #fn_name<
 				R: #crate_::Encode + #crate_::Decode + PartialEq,
 				NC: FnOnce() -> std::result::Result<R, #crate_::ApiError> + std::panic::UnwindSafe,

substrate/primitives/api/test/tests/runtime_calls.rs

@@ -59,7 +59,7 @@ fn calling_native_runtime_function_with_non_decodable_parameter() {
 		.build();
 	let runtime_api = client.runtime_api();
 	let block_id = BlockId::Number(client.chain_info().best_number);
-	runtime_api.fail_convert_parameter(&block_id, DecodeFails::new()).unwrap();
+	runtime_api.fail_convert_parameter(&block_id, DecodeFails::default()).unwrap();
 }
 
 #[test]