Shell logs: remove 'no prevalidator filter found' warning for protocol Genesis

Context

When starting a node, we get a no prevalidator filter found warning:

This is normal for protocol Genesis (which it doesn't have a plugin), so it shouldn't cause a warning. This has become all the more noticeable now that we have colored logs thanks to !8685 (merged).

This MR removes the warning when the protocol version is V0 (ie. the protocol is either Genesis or 000).

Manually testing the MR

Start a sandbox node:

./src/bin_node/octez-sandboxed-node.sh 1

• Before the MR, observe the warning for Genesis
• After the MR, the warning is no longer there
• After the MR, remove the line let () = Shell_plugin.register_filter (module Filter) from src/proto_alpha/lib_plugin/plugin_registerer.ml. Start a node again, and in another terminal, start a client and activate alpha:

eval $(src/bin_client/octez-init-sandboxed-client.sh 1)
octez-activate-alpha

Observe that the node still issues the no prevalidator filter found warning for alpha

Checklist

• n/a Document the interface of any function added or modified (see the coding guidelines)
• n/a Document any change to the user interface, including configuration parameters (see node configuration)
• n/a 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