Remove code which allowed designate-manage to attempt to escalate
privileges so that configuration files can be read by users who
normally wouldn't have access, but do have sudo access.
Simpler version of [1].
[1] I03063d2af14015e6506f1b6e958f5ff219aa4a87
Closes-Bug: 1611171
Change-Id: I013754da27e9dd13493bee1abfada3fbc2a004c0