fix a typo in rpz test

fix a typo in rpz test

"tcp-only" was not being tested correctly in the RPZ system test
because the option to the "digcmd" function that causes queries to
be sent via TCP was misspelled in one case, and was being interpreted
as a query name.

the "ckresult" function has also been changed to be case sensitive
for consistency with "digcmd".

(cherry picked from commit 78af071c11d21e2ce18ae2af0b384548c65a47e0)