Fix unexpected UnrequestedBlobId and ExtraBlocksReturned errors due to race conditions.

[jimmygchen]

Issue Addressed

Fix unexpected UnrequestedBlobId and ExtraBlocksReturned errors due to race conditions.

Scenario

1. Node receives a blob with unknown parent hash via gossip, this triggers a current lookup + parent lookup
2. Some blobs for the current lookup are received via gossip before we get RPC responses
3. RPC blob returned, this triggers UnrequestedBlobId as we already have the blob. This updates the lookup state to State::AwaitingDownload, which causes subsequent blobs received to trigger error ExtraBlocksReturned
4. This causes peers to be disconnected.

[realbigsean]

I think we should take out the block root check, and revert the deleted tests, but I'm on board with adding the BlockIsAlreadyKnown change and the error information improvement

[realbigsean]

Suggested change

	if expected_block_root == received_id.block_root {
	// We may have already received this blob via gossip since the lookup,
	// so don't return an error here.
	return Ok(None);
	}

I think the issue is really that we update requested_ids mid-response which keeps us from tracking what we should receive. If this is the case, this is more treating a symptom than the cause. This is an alternative:

77c4ffe#diff-af9c70c212795da7557f17c24d6fc12fa4aa6833d06db6eb2d807c277ee2aadbR260

[realbigsean]

closing in favor of #5488