Explicitly set scheduler_available_filters

Tempest's scheduler_available_filters has a special 'all' value that
is understood to mean 'all filters are enabled' by various tempest
tests. However, what it really means is 'the default nova filters are
enabled.' In an effort to help clean that up, this patch explicitly
sets scheduler_available_filters to nova's $FILTERS. Because $FILTERS
is now used in both lib/nova and lib/tempest, it is renamed
$NOVA_FILTERS.

Change-Id: I6ffc1e9989cd61d666f9c1db9c94fbabd7151918
Related-bug: 1628443
diff --git a/lib/tempest b/lib/tempest
index 60f571c..b8b313e 100644
--- a/lib/tempest
+++ b/lib/tempest
@@ -372,6 +372,11 @@
     iniset $TEMPEST_CONFIG compute-feature-enabled block_migration_for_live_migration ${USE_BLOCK_MIGRATION_FOR_LIVE_MIGRATION:-False}
     iniset $TEMPEST_CONFIG compute-feature-enabled live_migrate_back_and_forth ${LIVE_MIGRATE_BACK_AND_FORTH:-False}
     iniset $TEMPEST_CONFIG compute-feature-enabled attach_encrypted_volume ${ATTACH_ENCRYPTED_VOLUME_AVAILABLE:-True}
+
+    if [[ -n "$NOVA_FILTERS" ]]; then
+        iniset $TEMPEST_CONFIG compute-feature-enabled scheduler_enabled_filters ${NOVA_FILTERS}
+    fi
+
     if is_service_enabled n-cell; then
         # Cells doesn't support shelving/unshelving
         iniset $TEMPEST_CONFIG compute-feature-enabled shelve False