check-sanity skip checking q-fwaas and q-l3

FWaaS is running as a service plugin in neutron-server and doesn't have
any dedicated process. When Neutron is deployed with VPNaaS it's running
instead of l3-agent with the same capabilites as L3 agent has. Thus
checking whether processes for these services are running is not
necessary.

Change-Id: I8f438cfccc84be801d4064bdb564a95c6621bf55
(cherry picked from commit 49883a0270ede3dfdfe15bde2930c9df9bdc8c7f)