standalone test: Print 'almost' full guest OS name

So that we don't fall into the traps of 'shortnames',
that is, parts of the names that are not printed. For
example:

Win7.64

is in fact Win7.64.sp0, so if one puts only Win7.64 in
the command line, we'll execute both Win7.64.sp0 and
Win7.64.sp1. Printing a part of the full name avoids
that.
Signed-off-by: NLucas Meneghel Rodrigues <lmr@redhat.com>