Add for add-help-for-timeline-arg for timeline command (#7361)

## Problem

When calling `./neon_local timeline` a confusing error message pops up:
`command failed: no tenant subcommand provided`

## Summary of changes
Add `add-help-for-timeline-arg` for timeline commands so when no
argument for the timeline is provided help is printed.

control_plane/src/bin/neon_local.rs

@@ -1417,6 +1417,7 @@ fn cli() -> Command {
         .subcommand(
             Command::new("timeline")
             .about("Manage timelines")
+            .arg_required_else_help(true)
             .subcommand(Command::new("list")
                 .about("List all timelines, available to this pageserver")
                 .arg(tenant_id_arg.clone()))