Don't use "sudo -n" option, which is not supported by RHEL4.

It was added to avoid a password prompt when running tests. Jenkins
disables TTY access, so it should not be a problem there regardless,
but it may lead to cf-agent hanging on a password prompt when running
tests locally if sudoers is not set up correctly.
Fix leftover primary group causing trouble for later users tests.
Remove leftover comments.