Scheduler: remove test scheduling methods that are not used

The test code no longer uses the following methods:
 - fake_get_group_filtered_hosts
 - fake_get_group_filtered_affinity_hosts

This patch removes those methods.

Change-Id: I0a005fb1301ce78cc2ec365429015c08d58f446e
Merge "Scheduler: remove test scheduling methods that are not used"