labs: reorder setup_neutron_network.sh

This patch reorders the content of setup_neutron_network.sh to more
closely match the order of instructions in the install-guide, making it
easier to compare script and instructions.

Change-Id: Ifa5e23b3d9b0af321b907ab75bd62b171555750b
Co-Authored-By: Pranav Salunke <dguitarbite@gmail.com>
Merge "labs: reorder setup_neutron_network.sh"