Add new filter for Nova Scheduler

We need to use filter ServerGroupAffinityFilter
in nova.conf to fix issues with fails of several
Tempest tests. We want to deploy OpenStack cloud
which will pass all Tempest tests and in this case
we need to add this filter to Nova config file.

Change-Id: I3e74078d69917c295ca27a054610f78c186292bb
Closes-Bug: #1389701