Discard storage items under Ethereum pallet

[boundless-forest]

If we set up a new chain starting from 0, then most of the storage items in the Ethereum pallet seem useless.

Pending, CurrentBlock, CurrentReceipts, CurrentTransactionStatuses, and BlockHash are used to store the generated Ethereum-style Block, Transaction, and Receipt. Once the new chain starts, these storage items will be replaced with new data.

RemainingRingBalance and RemainingKtonBalance are also useless after the decimal update.

#[pallet::storage]
pub(super) type Pending<T: Config> = StorageValue<_, Vec<(Transaction, TransactionStatus, Receipt)>, ValueQuery>;

#[pallet::storage]
pub(super) type CurrentBlock<T: Config> = StorageValue<_, ethereum::BlockV2>;


#[pallet::storage]
pub(super) type CurrentReceipts<T: Config> = StorageValue<_, Vec<Receipt>>;


#[pallet::storage]
pub(super) type CurrentTransactionStatuses<T: Config> = StorageValue<_, Vec<TransactionStatus>>;


#[pallet::storage]
pub(super) type BlockHash<T: Config> = StorageMap<_, Twox64Concat, U256, H256, ValueQuery>;


#[pallet::storage]
#[pallet::getter(fn get_ring_remaining_balances)]
pub(super) type RemainingRingBalance<T: Config> =
	StorageMap<_, Blake2_128Concat, T::AccountId, u128, ValueQuery>;


#[pallet::storage]
#[pallet::getter(fn get_kton_remaining_balances)]
pub(super) type RemainingKtonBalance<T: Config> =
	StorageMap<_, Blake2_128Concat, T::AccountId, u128, ValueQuery>;