Address some Regression test failures

* Do not create an extra fip pool for public VN
* For VM reboots, retry a bit longer
* In VPC keypair setup, get the key from cfgm and then push it
to openstack
* Adapt to SG behavior change in test_ports_no_sg() test
* Change the call remove_any_method_from_cleanups()
* In one of the snat case, wait for vm to boot before doing snat tests

Change-Id: Ica0e51725290700043b8ce125e0c8fa114445f7b