De-duplicate payload from persisted beacon blocks

### Problem description

Since the merge, both execution and Lodestar beacon nodes persist the block's execution payload into the DB.

At an average block size of 100Kb, that's about 720 MB / day or 263 GB / year of redundant data we don't _really_ need to store. See https://ycharts.com/indicators/ethereum_average_block_size According to metrics, current Lodestar DB growth averaged over the last 30 days on a mainnet node without validator is 666 MB/day.

### Solution description

Instead Lodestar should persist in its DB blinded blocks, and retrieve from the execution node the payloads on demand to comply with:
- ReqResp beacon_blocks_by_root
- ReqResp beacon_blocks_by_range
- API requests involving the full block

All of this operations are not super time sensitive so the added latency is not a breaking deal

### Additional context

_No response_