Comment 61 for bug 1768230

I can confirm that the bug is back in initramfs-tools 0.130ubuntu3.3 (it was OK with 0.130ubuntu3.2)

The difference is even visible when running update-initramfs -u -k all (on 3.2 you see LVM name, on 3.3 you see UUID).
with initramfs-tools 0.130ubuntu3.2:
update-initramfs -u -k all
update-initramfs: Generating /boot/initrd.img-4.15.0-34-generic
I: The initramfs will attempt to resume from /dev/dm-1
I: (/dev/mapper/vg_system-lv_swap)
I: Set the RESUME variable to override this.

=> no delay while booting

and with initramfs-tools 0.130ubuntu3.3:
update-initramfs -u -k all
update-initramfs: Generating /boot/initrd.img-4.15.0-34-generic
I: The initramfs will attempt to resume from /dev/dm-1
I: (UUID=c2849fd0-bfeb-11e8-82df-e63cc106402d)
I: Set the RESUME variable to override this.

=> delay 30s while booting