The current logic to set public network is get the first public
network from neutronclien, but this network could only be seen
by only one tenant for rbac policy, this will cause testcase fail.
Now modify the logic, get the public network which can be seen
by all tenants.
Also if there is no rbac policy, we still use the first public
network.
Closes-Bug: #1809111
Change-Id: I565ec563abc0ffe22643d88e79f64c6980f2ca21
Signed-off-by: Yang Li <yang.li@easystack.cn>
9420df764b