Change --insecure to ignore the --os-cacert setting. This is a change
from before where OSC followed the requests pattern of cacert taking
priority.
This logic is also introduced in os-client-config 1.3.0; we
do not require that release yet so it is duplicated here for now.
That change will come with the upcoming global options refactor.
Closes-Bug: #1447784
Change-Id: Iaa6d499ed0929c00a56dcd92a2017487c702774a
31d785ec69