In I4b5a32a15d WCT tests invocation was switched from bazel to
bazelisk, but bazelisk location command was wrong. stderr and
stdout was erroneously redirected to the /dev/null, so that the
actual location of the bazelisk command was lost. Fix the location
detection command by redirecting only stderr but not stdout to the
null device.
Change-Id: I66cb33e0074675e00b0e58bb11413b5151a57533