Description of problem:

During tests for https://bugzilla.redhat.com/show_bug.cgi?id=2159288 we found another grubenv configuration that could also make leapp upgrade fail.

How reproducible:
Always

Steps to Reproduce:
1. Get a 7.9 machine, install leapp-upgrade, run leapp preupgrade until it has no inhibitors and the report is successful
2. cd into the directory where grubenv is located
3. execute:

truncate --size=1023 grubenv
echo -n 'a' >> grubenv

4. run leapp preupgrade (it does not inhibit)
5. run leapp upgrade (it works).
6. reboot

Actual results:
On reboot, the wrong grub entry is selected by default. If the correct entry is manually selected (upgrade initramfs), the machine ends up in emergency shell.

Expected results:
Inhibit leapp upgrade if such a format is found in grubenv.

Additional info:
Test MR (the test is already written and for now the test case will be commented out until this is resolved): https://gitlab.cee.redhat.com/oamg/leapp-tests/-/merge_requests/214