Deprecate `dmp-queue` pallet (#4475)
`cumulus-pallet-dmp-queue` is not needed anymore since https://github.com/paritytech/polkadot-sdk/pull/1246. The only logic that remains in the pallet is a lazy migration in the [`on_idle`](https://github.com/paritytech/polkadot-sdk/blob/8d62c13b /cumulus/pallets/dmp-queue/src/lib.rs#L158) hook. --------- Signed-off-by: Oliver Tale-Yazdi <[email protected]>