test-copy: remove unnecessary initialization

test-copy: remove unnecessary initialization

Initializing just some of the values doesn't make sense. We should handle them
all in the same way. In those tests there are no jumps, all steps are covered
with assert_se(), so we know everything will be set if we get to the end of the
function. And _not_ initializing those variables has the advantage that it
allows valgrind to catch potential initalization errors in the function being
tested.