Install and setup cloud-init for Vagrant images

[JonTheNiceGuy]

Following a brief discussion on the Mattermost, I've implemented a fix to #299 - I have not implemented this change in the generic cloud image. I've been unable to test the change using tests/vagrant/ as the version of testinfra doesn't recognise the flags --hosts= and --ssh-config= on my host.

[JonTheNiceGuy]

Just to confirm, when I tested this with packer build -only=virtualbox-iso.almalinux_10_vagrant_virtualbox_x86_64 . and then launched a vagrant image using vagrant 2.4.9 and this built box, it provisioned perfectly with the cloud-init. I then re-tested with -only=virtualbox-iso.almalinux-9 and this also performed exactly as expected.