kola: Fix path for qemu-bios argument

[pothos]

• kola: Align qemu-unpriv with qemu after new additions

  The qemu-unpriv platform doesn't support as many test scenarious as the
  priv. qemu platform but it is still useful for testing. When doing
  changes in the qemu platform we should also do them for qemu-unpriv.
  Port the last changes over to get swtpm support.

• kola: Fix path for qemu-bios argument

  After changing the qemu working directory, relative qemu-bios path
  arguments stopped working.
  Handle relative paths by prepending kola's current working directory.
  The changes from
  git diff --no-index platform/machine/qemu/ platform/machine/unprivqemu/
  show that only platform-specific options differ. As a test
  cl.tpm.root-cryptenroll passed for --platform=qemu and
  --platform=qemu-unpriv when run with
  --qemu-bios=flatcar_production_qemu_uefi_efi_code.fd as relative path
  argument.

How to use

This should fix the qemu_uefi nightly failure

Testing done

Local testing as mentioned above:

./kola run -d --platform=qemu-unpriv --qemu-bios=/var/tmp/flatcar_production_qemu_uefi_efi_code.fd --qemu-image /var/tmp/flatcar_production_image.bin cl.basic
./kola run -d --platform=qemu-unpriv --qemu-bios=flatcar_production_qemu_uefi_efi_code.fd --qemu-image /var/tmp/flatcar_production_image.bin cl.tpm.root-cryptenroll
sudo ./kola run -d --platform=qemu --qemu-bios=flatcar_production_qemu_uefi_efi_code.fd --qemu-image /var/tmp/flatcar_production_image.bin cl.tpm.root-cryptenroll