lava: Switch to `os: apertis` after upgrade to LAVA 2021.05

With the update to LAVA 2021.05 a new deployment type has been added to
ensure that things work despite:

1. `/bin/sh` not pointing to Bash
2. a read-only `/` that prevents unpacking the overlay there

In particular the latter causes all the OSTree tests to fail when
downloading and unpacking the overlay with:

    ./lava-4147029/
    tar: ./lava-4147029: Cannot mkdir: Operation not permitted

See https://gitlab.collabora.com/lava/lava/-/commit/d621f93191591714449e67945ebd95cb6396727a


for the commit introducting the `apertis` type.

Signed-off-by: Emanuele Aina <emanuele.aina@collabora.com>

lava/common-boot-tpl.yaml

@@ -93,7 +93,7 @@ actions:
         bmap:
           url: {{boot.image_url('bmap')}}
       uniquify: false
-      os: ubuntu
+      os: apertis
       writer:
         tool: /usr/bin/bmaptool
         options: copy {DOWNLOAD_URL} {DEVICE}

lava/common-qemu-boot-tpl.yaml

@@ -52,7 +52,7 @@ actions:
           image_arg: -m 1024 -enable-kvm -cpu host -vga qxl -device virtio-rng-pci -drive if=pflash,format=raw,readonly,file=/usr/share/ovmf/OVMF.fd -drive if=virtio,format=raw,file={rootfs}
           url: {{boot.image_url('gz')}}
           compression: gz
-      os: ubuntu
+      os: apertis
 
   - boot:
       namespace: system

lava/group-nfs-tpl.yaml

@@ -56,7 +56,7 @@ actions:
       ramdisk:
         url: {{baseurl}}/{{imgpath}}/{{image_date}}/{{arch}}/nfs/initrd.img
         compression: gz
-      os: ubuntu
+      os: apertis
       {% if needs_dtb -%}
       dtb:
         url: {{baseurl}}/{{imgpath}}/{{image_date}}/{{arch}}/nfs/dtbs/{{dtb}}