pallet-scheduler: Fix migrations V2 to V3 (#10757)

* pallet-scheduler: Fix migrations V2 to V3

V2 already supported origins, so we need to move them over instead of setting it to `Root`. Besides
that it also removes the custom `Releases` enum and moves it over to `StorageVersion`.

* Fixes

* Fixes

* 🤦

substrate/bin/node/testing/src/genesis.rs

@@ -91,7 +91,6 @@ pub fn config_endowed(code: Option<&[u8]>, extra_endowed: Vec<AccountId>) -> Gen
 		assets: Default::default(),
 		gilt: Default::default(),
 		transaction_storage: Default::default(),
-		scheduler: Default::default(),
 		transaction_payment: Default::default(),
 	}
 }