Split out compute filters unit tests

It's a terribly-named filter, the ComputeFilter, since it does nothing
other than inspect the service disabled field and the servicegroup API.
Regardless, we move these unit tests out into their own file.

Change-Id: I8655634f947c68b0a26eae40f8357137138a900a
Splits out retry filter unit tests

Breaks out the retry filter unit tests from the test_host_filters.py
file into their own test file.

Change-Id: I2e7e81bd374048d22e19b45d3d43e7762fe82332
Merge "Split out compute filters unit tests"
Merge "Splits out retry filter unit tests"