EIP-6916 - Client should automatically restart for Ephemery testnet

[0xEllie]

When the --network is Ephemery, the client should restart automatically at the due cycle, which is 28 days.

This issue is a prerequisite for handling other Ephemery-Besu related issues such as DB reset here #8180 .

Even if the Ephemery supposedly doesn't require a fresh database at the beginning of each cycle, this issue still persists because a network restart is necessary to prevent manual handling of the client.