Support old finalized checkpoints in assertPeerRelevance

[dapplion]

From #3405

TODO: If the slot is very old, go to the historical blocks DB and fetch the block with less or equal slot. Note that our db schema will have to be updated to persist the block root to prevent re-hashing. For now peers will be accepted, since it's better than throwing an error on getBlockRootAtSlot()

lodestar/packages/lodestar/src/network/peers/utils/assertPeerRelevance.ts

Lines 97 to 99 in fbeabc6

	// TODO: If the slot is very old, go to the historical blocks DB and fetch the block with less or equal `slot`.
	// Note that our db schema will have to be updated to persist the block root to prevent re-hashing.
	// For now peers will be accepted, since it's better than throwing an error on `getBlockRootAtSlot()`

[philknows]

Low priority. Find the permalink reference in the code and potentially close @wemeetagain