vm-under-test: Permanently disable swap space

Disabling swap space since it will introduce potential latency.
In order to permanently disable [0], this commit is:
- using the swapoff command.
- commenting the swap entries on /etc/fstab.
- masking the swap service with systemctl (done during the first-boot)

[0]
https://askubuntu.com/questions/440326/how-can-i-turn-off-swap-permanently/984777#984777

Signed-off-by: Ram Lavi <ralavi@redhat.com>

vms/vm-under-test/scripts/customize-vm

@@ -25,3 +25,6 @@ systemctl disable irqbalance
 
 dnf --enablerepo=rt install -y tuned-profiles-realtime
 dnf --enablerepo=nfv install -y tuned-profiles-nfv-guest
+
+swapoff -a
+sed -i '/swap/s/^/#/' /etc/fstab

vms/vm-under-test/scripts/first-boot

@@ -19,6 +19,8 @@
 
 set -e
 
+systemctl mask "$(systemctl --type swap | grep '.swap' | awk '{print $1}')"
+
 echo isolated_cores=1-2 >> /etc/tuned/realtime-virtual-guest-variables.conf
 echo isolate_managed_irq=Y >> /etc/tuned/realtime-virtual-guest-variables.conf
 tuned-adm profile realtime-virtual-guest