EVM Node: Halt block production before sequencer upgrade

Closes L2-200

What

This patch introduces a mechanism to temporarily halt block production by the Etherlink sequencer five minutes prior to a planned sequencer operator upgrade. This ensures a controlled shutdown of block production activities.

Why

Halting block production before a sequencer upgrade is crucial for ensuring a smooth and safe transition. It minimizes the risk of issues that could arise from producing blocks during the upgrade process, such as missed blocks, inconsistent state, or transaction failures, thereby contributing to the overall stability and reliability of the Etherlink network.

How

The block producer now checks for a pending sequencer upgrade event. If an upgrade is scheduled, and the current timestamp is within five minutes of the upgrade's timestamp, the block production process is skipped for that specific block. This check is distinct from the existing kernel upgrade check.

Manually testing the MR

dune exec -- etherlink/tezt/tests/main.exe --verbose sunset alpha latest --only 1

and look for

[09:45:56.492] [sequencer_evm_node1] Jul 10 11:45:56.491  ERROR │ transaction pool and block production are locked

to confirm it works indeed.

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
• Document any change to the user interface, including configuration parameters (see node configuration)
• Provide automatic testing (see the testing guide).
• For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
• Select suitable reviewers using the Reviewers field below.
• Select as Assignee the next person who should take action on that MR