lakebox: hide the subcommand from the top-level help listing

Mark the lakebox parent command as Hidden so it doesn't appear in
'databricks --help' under Developer Tools. The subcommands themselves
are still reachable — 'databricks lakebox --help' lists them — but the
feature stays out of the discoverable surface while it remains
internal.

This also reverts the acceptance/help/output.txt regen from the
previous push, since hiding the command means the golden file already
matches the actual help output.

Co-authored-by: Isaac

Author: pietern

cmd/lakebox/lakebox.go

@@ -9,6 +9,7 @@ func New() *cobra.Command {
 		Use:     "lakebox",
 		Short:   "Manage Databricks Lakebox environments",
 		GroupID: "development",
+		Hidden:  true,
 		Long: `Manage Databricks Lakebox environments.
 
 Lakebox provides SSH-accessible development environments backed by