Subcommands not listed automatically in CLI help

The help command in the CLI framework was disabled in 0827743e due to races in our tests. The CLI framework is sharing the help command between multiple App instances and reading and writing into it concurrently. Disabling the help command avoids these races.

Disabling the help command caused a regression in our CLI help text where the subcommands are no longer automatically listed.

Output before the change 0827743e~1:

NAME:
   praefect configuration - manages configuration

USAGE:
   praefect configuration command [command options] [arguments...]

COMMANDS:
   validate  validates configuration
   help, h   Shows a list of commands or help for one command

OPTIONS:
   --help, -h  show help

Output after the change 0827743e:

NAME:
   praefect configuration - manages configuration

USAGE:
   praefect configuration [command options] [arguments...]

OPTIONS:
   --help, -h  show help

This has led to manually documenting the subcommands via the description. As this is difficult to maintain, we should fix the regression and have the subcommands documented automatically again.