Split and fix the type filters unit tests

The unit test for TypeAffinityFilter was broken -- it was passing in the
instance_type['name'] key, when the filter class actually checks the
'id' key of the instance_type property of the filter_properties dict. :(

This corrects the tests, removes all DB accesses from both the type and
aggregate type affinity filter unit tests, and splits them out into
their own test file.

Change-Id: I5fc27c538cc419b4ed972839751e0e779151fc58
Merge "Split and fix the type filters unit tests"