simulators/ethereum/sync: reduce finalized block distance to zero

[RomanHodulak]

Currently, the ethereum/sync test waits for the other peer to sync to head block.

However, the other peer only syncs to latest finalized block.

This test will therefore never pass if the latest finalized block is not the head block.

This was not a problem until this commit 8d692b4 introduced a finalized distance of fifty.

Hence, the solution is to reduce the finalized distance to zero.

This change matches the original behavior of the test before it started failing for most of the clients.

[fjl]

Thanks for the comment. I added the finalized distance as an experiment because there were some issues. I'm curious to hear why you say the client only syncs to the finalized block? Why does it not sync to the head block?