[chore]: Remove deprecated types and migrations after new Schemas and Intents deployed on Mainnet

[JoeCap08055]

Feature Description

Details

Once the new Schemas and Intents model has been deployed on Mainnet and the migrations have successfully completed, we can remove the following from the code:

• [ ] Schemas pallet migration V4 -> V5
• [ ] Messages pallet migration V2 -> V3
• [ ] Stateful storage migration V1 -> V2
• [ ] Deprecated types in schemas pallet
• [ ] Deprecated types in messages pallet
• [ ] Deprecated types in stateful-storage pallet

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