[vtctldclient] Update CLI entrypoint for GetBackups
[vtctldclient] Update CLI entrypoint for GetBackups

We're not including the Detailed fields here yet, because they are
unused in the server implementation (for now).

Signed-off-by: Andrew Mason <8a240ff75aa1467ba5eba4db0c8200b61262547e@slack-corp.com>

mahak/vitess,vitessio/vitess,tinyspeck/vitess,tinyspeck/vitess,mahak/vitess,mahak/vitess,vitessio/vitess,mahak/vitess,tinyspeck/vitess,mahak/vitess,mahak/vitess,tinyspeck/vitess,vitessio/vitess,vitessio/vitess,mahak/vitess,tinyspeck/vitess,vitessio/vitess,vitessio/vitess,mahak/vitess,vitessio/vitess,tinyspeck/vitess,tinyspeck/vitess,vitessio/vitess