ci: install qemu-system-x86 for the 26.04 runners

Ubuntu 26.04 turned qemu-kvm into a virtual package with no installation
candidate, so every run that installs it dies before the VM boot test
and the integration landscape. qemu-system-x86 is the real package that
provides it.

Author: fwiesel

.github/actions/test/integration/dependencies/action.yml

@@ -10,7 +10,7 @@ runs:
         sudo apt-get install -y \
           parted \
           squashfs-tools \
-          qemu-kvm \
+          qemu-system-x86 \
           genisoimage \
           libvirt-daemon-system \
           libvirt-clients \