`limactl start template://<TAB>` should not print private snippets (`_default/*`, `_images/*`, ...)

[AkihiroSuda]

$ limactl start template://<TAB>
//_default/mounts                   //almalinux                         //experimental/wsl2
//_images/almalinux-8               //almalinux-8                       //faasd
//_images/almalinux-9               //almalinux-9                       //fedora
//_images/alpine                    //alpine                            //fedora-41
//_images/alpine-iso                //alpine-iso                        //fedora-42
//_images/archlinux                 //apptainer                         //k3s
//_images/centos-stream-10          //apptainer-rootful                 //k8s
//_images/centos-stream-9           //archlinux                         //linuxbrew
//_images/debian-11                 //buildkit                          //opensuse
//_images/debian-12                 //centos-stream                     //opensuse-leap
//_images/fedora                    //centos-stream-10                  //oraclelinux
//_images/fedora-41                 //centos-stream-9                   //oraclelinux-8
//_images/fedora-42                 //debian                            //oraclelinux-9
//_images/opensuse-leap             //debian-11                         //podman
//_images/oraclelinux-8             //debian-12                         //podman-rootful
//_images/oraclelinux-9             //default                           //rocky
//_images/rocky-8                   //docker                            //rocky-8
//_images/rocky-9                   //docker-rootful                    //rocky-9
//_images/ubuntu                    //experimental/alsa                 //ubuntu
//_images/ubuntu-20.04              //experimental/debian-sid           //ubuntu-20.04
//_images/ubuntu-22.04              //experimental/gentoo               //ubuntu-22.04
//_images/ubuntu-24.04              //experimental/opensuse-tumbleweed  //ubuntu-24.04
//_images/ubuntu-24.10              //experimental/rke2                 //ubuntu-24.10
//_images/ubuntu-25.04              //experimental/u7s                  //ubuntu-25.04
//_images/ubuntu-lts                //experimental/vnc                  //ubuntu-lts

Private snippets (_default/*, _images/*, ...) should not be printed here.

UX "regression" in:

• Refactor images lists and default mounts into base templates #3453