Comment 18 for bug 1732028

In a discussion with smoser we decided to try just clearing /etc/fstab - it might be sufficient for our test intention and at the same time avoid the issue.
With that done we still have the following failing with timeouts:
  [ TIME ] Timed out waiting for device dev-ttyS0.device.
  [FAILED] Failed to start Journal Service.

Not sure why the first happens, but the second is due to the lack of a root FS.

In my slowed down environments it boots REALLY slow then, like 30 minutes.
Several services are unforgiving of the root not being there.
Especially snap that was getting into a loop of Starting/Stopping/... and by that did not let it complete.

The former try was too hard (intentionally), so I stepped back to just replace the labels with the (in this case) known partition IDs /dev/sda1 and /dev/sda15.
This I first booted non slowed to check if the config works at all.
It works

Note: non slowed the TCG-system is at 4*100% for the vcpus and 400% for TCG. ~800% vs ~98% is a slowdown by 1/8 which matches what I see as effective slowdown.

A few more tries together with Scott found that disabling the fstab entry for EFI, but keeping the main root as-is.
Again we verified this config is valid (boot without CPU limit) and then we set the limit.
With that finally it seems to work.
Lets code that up in open-iscsi and put it to a PPA to test on LP infra against it.