Fix make distcheck after the new shell tests

With the new shell tests, we have for the first time the situation
where tests require a binary built (via make), but the binary itself
is not the test. Hence, we need to declare and use check_SCRIPTS for
it.

Also corrects a wrong file name (introduced during rebase/editing the
patch series).

The end result is that `make distcheck` now passes.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>