common: no need to parse config file in new

common: no need to parse config file in new

I saw "new" failed the TEST_DEV/SCRATCH_DEV validation when TEST_DEV or
SCRATCH_DEV points to directory, which is needed in overlayfs testing.

"new" only generates test template and doesn't need common/config to
parse and validate TEST_DEV/SCRATCH_DEV etc., so just returns after
setting all needed commands.

Signed-off-by: Eryu Guan <eguan@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>