tests: Add coverage for PCI use with isapc and microvm

tests: Add coverage for PCI use with isapc and microvm

Neither machine type supports PCI, so attempting to add a
PCI controller should fail. It currently doesn't, and we're
going to address that in an upcoming commit.

Note that the domain gets a PCI memballoon device added
automatically. That also shouldn't happen, and will similarly
be fixed.

Signed-off-by: Andrea Bolognani <abologna@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>