RFE: catch "efibootmgr -C" error

Description of problem:

Customers upgrading VMWare VMs may face an issue were "efibootmgr -C" fails to create the new entry for the Leapp Upgrade kernel because of "No space left on device" (actor "efi_interim_fix"):
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
... leapp.workflow.InterimPreparation: Executing actor efi_interim_fix
... leapp.workflow.InterimPreparation.efi_interim_fix: External command has started: ['/sbin/efibootmgr']
... leapp.workflow.InterimPreparation.efi_interim_fix: BootCurrent: 0005
... leapp.workflow.InterimPreparation.efi_interim_fix: BootOrder: 0005,0000,0001,0002,0003,0004
... leapp.workflow.InterimPreparation.efi_interim_fix: Boot0000* EFI Virtual disk (0.0)
... leapp.workflow.InterimPreparation.efi_interim_fix: Boot0001* EFI Virtual disk (1.0)
... leapp.workflow.InterimPreparation.efi_interim_fix: Boot0002* EFI VMware Virtual SATA CDROM Drive (0.0)
... leapp.workflow.InterimPreparation.efi_interim_fix: Boot0003* EFI Network
... leapp.workflow.InterimPreparation.efi_interim_fix: Boot0004* EFI Internal Shell (Unsupported option)
... leapp.workflow.InterimPreparation.efi_interim_fix: Boot0005* Red Hat Enterprise Linux
... leapp.workflow.InterimPreparation.efi_interim_fix: External command has finished: ['/sbin/efibootmgr']
... leapp.workflow.InterimPreparation.efi_interim_fix: External command has started: ['/sbin/efibootmgr', '-n', u'0005']
... leapp.workflow.InterimPreparation.efi_interim_fix: Could not set BootNext: No space left on device
... leapp.workflow.InterimPreparation.efi_interim_fix: Command ['/sbin/efibootmgr', '-n', u'0005'] failed with exit code 13.
... leapp.workflow.InterimPreparation.efi_interim_fix: External command has finished: ['/sbin/efibootmgr', '-n', u'0005']
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

The issue happens when VMWare VM has a too small NVRAM file.
It would be nice to point to the KCS I just wrote: https://access.redhat.com/solutions/7023631

This KCS is VMWare specific. If the issue happens on other hardware, then likely there is some Firmware issue to deal with.

Version-Release number of selected component (if applicable):

all releases

How reproducible:

Always

Steps to Reproduce:
1. Create a VMWare VM at Hardware Level 13 in UEFI
2. Install RHEL7 and update it
3. Try to leapp it

Actual results:

See above

Expected results:

Error + KCS