labs: don't source labs-openstackrc.sh

Setup_neutron_network.sh attempts to source a file that has been
renamed. Because the script doesn't need authentication, we can
just remove the reference to the file.

Change-Id: Ie5c1c6bf8bda87b0e7cca9ec92aa86c53e866ff4
Merge "labs: don't source labs-openstackrc.sh"