gitlab_runner: Disable slow/unneeded systemd-time-wait-sync in the VM image

The service was enabled in arch-boxes to account for "hardware clock is
not in UTC, but instead UTC+X"[1], in our case the (VM) hardware clock
is in UTC and we therfor don't need the slow systemd-time-wait-sync
service (+30 seconds).

[1] arch-boxes@e23d3c57

roles/gitlab_runner/files/libvirt-executor-update-base-image

@@ -32,7 +32,7 @@ arch-chroot mnt pacman-key --populate
 
 # shellcheck disable=SC2016
 printf 'Server = https://geo.mirror.pkgbuild.com/$repo/os/$arch' > mnt/etc/pacman.d/mirrorlist
-arch-chroot mnt systemctl disable reflector-init
+arch-chroot mnt systemctl disable reflector-init systemd-time-wait-sync
 arch-chroot mnt pacman -Sy --noconfirm --needed archlinux-keyring
 arch-chroot mnt pacman -Syu --noconfirm --needed git git-lfs gitlab-runner
 sed -E 's/^#(IgnorePkg *=)/\1 linux/' -i mnt/etc/pacman.conf