[testnet] Align testnet system parachain runtimes using RelayTreasuryLocation and SystemParachains in the same way (#2023)

This PR addresses several issues:
- simplify referencing `RelayTreasuryLocation` without needing
additional `RelayTreasury` struct
- fix for referencing `SystemParachains` from parachain with `parents:
1` instead of `parents: 0`
- removed hard-coded constants and fix tests for `asset-hub-rococo`
which was merged to master after
https://github.com/paritytech/polkadot-sdk/pull/1726

---------

Co-authored-by: command-bot <>

cumulus/parachains/runtimes/contracts/contracts-rococo/src/xcm_config.rs

@@ -20,7 +20,7 @@ use super::{
 use crate::common::rococo::currency::CENTS;
 use frame_support::{
 	match_types, parameter_types,
-	traits::{ConstU32, EitherOfDiverse, Everything, Nothing},
+	traits::{ConstU32, EitherOfDiverse, Equals, Everything, Nothing},
 	weights::Weight,
 };
 use frame_system::EnsureRoot;
@@ -31,7 +31,7 @@ use parachains_common::{
 };
 use polkadot_parachain_primitives::primitives::Sibling;
 use polkadot_runtime_common::xcm_sender::ExponentialPrice;
-use rococo_runtime_constants::system_parachain::SystemParachains;
+use rococo_runtime_constants::system_parachain;
 use sp_runtime::traits::AccountIdConversion;
 use xcm::latest::prelude::*;
 use xcm_builder::{
@@ -52,6 +52,7 @@ parameter_types! {
 	pub UniversalLocation: InteriorMultiLocation = Parachain(ParachainInfo::parachain_id().into()).into();
 	pub const ExecutiveBody: BodyId = BodyId::Executive;
 	pub TreasuryAccount: Option<AccountId> = Some(TREASURY_PALLET_ID.into_account_truncating());
+	pub RelayTreasuryLocation: MultiLocation = (Parent, PalletInstance(rococo_runtime_constants::TREASURY_PALLET_ID)).into();
 }
 
 /// We allow root and the Relay Chain council to execute privileged collator selection operations.
@@ -140,8 +141,12 @@ pub type Barrier = TrailingSetTopicAsId<
 					// If the message is one that immediately attempts to pay for execution, then
 					// allow it.
 					AllowTopLevelPaidExecutionFrom<Everything>,
-					// Parent and its pluralities (i.e. governance bodies) get free execution.
-					AllowExplicitUnpaidExecutionFrom<ParentOrParentsPlurality>,
+					// Parent, its pluralities (i.e. governance bodies) and relay treasury pallet
+					// get free execution.
+					AllowExplicitUnpaidExecutionFrom<(
+						ParentOrParentsPlurality,
+						Equals<RelayTreasuryLocation>,
+					)>,
 					// Subscriptions for version tracking are OK.
 					AllowSubscriptionsFrom<ParentOrSiblings>,
 				),
@@ -152,6 +157,26 @@ pub type Barrier = TrailingSetTopicAsId<
 	>,
 >;
 
+match_types! {
+	pub type SystemParachains: impl Contains<MultiLocation> = {
+		MultiLocation {
+			parents: 1,
+			interior: X1(Parachain(
+				system_parachain::ASSET_HUB_ID |
+				system_parachain::BRIDGE_HUB_ID |
+				system_parachain::CONTRACTS_ID |
+				system_parachain::ENCOINTER_ID
+			)),
+		}
+	};
+}
+
+/// Locations that will not be charged fees in the executor,
+/// either execution or delivery.
+/// We only waive fees for system functions, which these locations represent.
+pub type WaivedLocations =
+	(RelayOrOtherSystemParachains<SystemParachains, Runtime>, Equals<RelayTreasuryLocation>);
+
 pub type TrustedTeleporter = ConcreteAssetFromSystem<RelayLocation>;
 
 pub struct XcmConfig;
@@ -174,12 +199,7 @@ impl xcm_executor::Config for XcmConfig {
 	type MaxAssetsIntoHolding = ConstU32<8>;
 	type AssetLocker = ();
 	type AssetExchanger = ();
-	type FeeManager = XcmFeesToAccount<
-		Self,
-		RelayOrOtherSystemParachains<SystemParachains, Runtime>,
-		AccountId,
-		TreasuryAccount,
-	>;
+	type FeeManager = XcmFeesToAccount<Self, WaivedLocations, AccountId, TreasuryAccount>;
 	type MessageExporter = ();
 	type UniversalAliases = Nothing;
 	type CallDispatcher = RuntimeCall;