contracts: Move Schedule from Storage to Config (#8773)

* Move `Schedule` from Storage to Config

* Updated CHANGELOG

* Fix nits from review

* Fix migration

* Print the debug buffer as tracing message

* Use `debug` instead of `trace` and update README

* Add additional assert to test

* Rename `schedule_version` to `instruction_weights_version`

* Fixed typo

* Added more comments to wat fixtures

* Add clarification for the `debug_message` field

substrate/frame/contracts/src/migration.rs

@@ -15,24 +15,23 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use crate::{Config, Weight, CurrentSchedule, Pallet, Schedule};
-use frame_support::traits::{GetPalletVersion, PalletVersion, Get};
+use crate::{Config, Weight, Pallet};
+use frame_support::{
+	storage::migration,
+	traits::{GetPalletVersion, PalletVersion, PalletInfoAccess, Get},
+};
 
 pub fn migrate<T: Config>() -> Weight {
 	let mut weight: Weight = 0;
 
 	match <Pallet<T>>::storage_version() {
-		// Replace the schedule with the new default and increment its version.
 		Some(version) if version == PalletVersion::new(3, 0, 0) => {
-			weight = weight.saturating_add(T::DbWeight::get().reads_writes(1, 1));
-			let _ = <CurrentSchedule<T>>::translate::<u32, _>(|version| {
-				version.map(|version| Schedule {
-						version: version.saturating_add(1),
-						// Default limits were not decreased. Therefore it is OK to overwrite
-						// the schedule with the new defaults.
-						.. Default::default()
-					})
-			});
+			weight = weight.saturating_add(T::DbWeight::get().writes(1));
+			migration::remove_storage_prefix(
+				<Pallet<T>>::name().as_bytes(),
+				b"CurrentSchedule",
+				b"",
+			);
 		}
 		_ => (),
 	}