Run the sh(1) and test(1) tests as unprivileged.

One of the tests for test(1) fails and some of the tests for sh(1) are
silently bypassed when running as root.

To fix these tests and ensure they all run, mark the test programs for
sh(1) and test(1) as requiring an unprivileged user. (This should and
will be the default in Kyua but isn't yet.)

MFC after: 1 week