Conductor instance_get_all replaces _by_filters

Updates the Nova conductor so that it uses instance_get_all()
and instance_get_all_by_host() from the Nova DB API to
implement its own like named functions.

This fixes a regression that occured in d22b0ca where we switched
from using the DB API's instance_get_all_by_host and instance_get_all
methods over to the DB APIs instance_get_all_by_filters.

This caused some subtle regressions due to the fact that
instance_get_all_by_filters has different defaults for
deleted records.

The previously used (prior to d22b0ca) instance_get_all() and
instance_get_all_by_host() functions rely on the context.read_deleted
and also handle the display of deleted and soft deleted records differently.

Fixes LP Bug #1096972.

Change-Id: Icb587ef169d1d7dd86cf6ee682e74bd4e84c37e2
Merge "Conductor instance_get_all replaces _by_filters"