Simplify closestJustifiedBalancesStateToCheckpoint

[twoeths]

Problem description

The assumption of this function is not correct anymore because we can store a lot of checkpoint states after n-historical-state flag implemented

lodestar/packages/beacon-node/src/chain/chain.ts

Line 1009 in b255111

const {state, stateId, shouldWarn} = this.closestJustifiedBalancesStateToCheckpoint(checkpoint, blockState);

Solution description

switch to async function, use PersistentCheckpointStateCache.getStateOrBytes()
if it returns a Uint8Array, loop through it to extract effective balances of active validators

Additional context

No response