fix net-create call for public1 in tools/init-runonce

The --router:external option is a boolean flag that doesn't take a value
(neutron client version 2.5.0). Passing True results in the following
error:

Invalid values_specs True

This patch simply removes the 'True' value.

Change-Id: If4b5305f37d50c14c767393eb21223b0e0b59494