Default not implemented for non-std builds for PersistedValidationData (#1207)

* Default not implemented for non-std builds for PersistedValidationData

* Remove v1

* Remove v1 for v2, this time correct

* More reverts of v1 for v2

* Update pallets/parachain-system/src/lib.rs

* fmt

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

cumulus/pallets/parachain-system/src/lib.rs

@@ -1049,7 +1049,14 @@ impl<T: Config> BlockNumberProvider for RelaychainBlockNumberProvider<T> {
 	}
 	#[cfg(feature = "runtime-benchmarks")]
 	fn set_block_number(block: Self::BlockNumber) {
-		let mut validation_data = Pallet::<T>::validation_data().unwrap_or_default();
+		let mut validation_data = Pallet::<T>::validation_data().unwrap_or_else(||
+			// PersistedValidationData does not impl default in non-std
+			PersistedValidationData {
+				parent_head: vec![].into(),
+				relay_parent_number: Default::default(),
+				max_pov_size: Default::default(),
+				relay_parent_storage_root: Default::default(),
+			});
 		validation_data.relay_parent_number = block;
 		ValidationData::<T>::put(validation_data)
 	}