init_cinder() shouldn't always create DEFAULT_VOLUME_GROUP_NAME

DEFAULT_VOLUME_GROUP_NAME volume group is LVM ephemeral storage used by
Nova. It is created by init_nova() if user sets NOVA_BACKEND to "LVM".
However, init_cinder() is also hardcoded to create it, based on the
asumption that CINDER_ENABLED_BACKENDS includes it. That assumption
doesn't hold for the current code. What's more important, even if user
wants to use DEFAULT_VOLUME_GROUP_NAME as one of cinder backends and
adds it to CINDER_ENABLED_BACKENDS, the current code in init_cinder()
are general enough and should work fine. This change removes relevant
code in init_cinder(). It also moves DEFAULT_VOLUME_GROUP_NAME clean-up
code from unstack.sh to cleanup_nova().

Change-Id: I53762f8eda6256f962cc4e1f1098406879bbcf5c
diff --git a/lib/cinder b/lib/cinder
index 3a8097f..e0b8971 100644
--- a/lib/cinder
+++ b/lib/cinder
@@ -420,10 +420,6 @@
             be_type=${be%%:*}
             be_name=${be##*:}
             if type init_cinder_backend_${be_type} >/dev/null 2>&1; then
-                # Always init the default volume group for lvm.
-                if [[ "$be_type" == "lvm" ]]; then
-                    init_default_lvm_volume_group
-                fi
                 init_cinder_backend_${be_type} ${be_name}
             fi
         done
diff --git a/lib/nova b/lib/nova
index 56e3093..ee682db 100644
--- a/lib/nova
+++ b/lib/nova
@@ -264,6 +264,10 @@
     stop_process "n-api-meta"
     remove_uwsgi_config "$NOVA_UWSGI_CONF" "$NOVA_UWSGI"
     remove_uwsgi_config "$NOVA_METADATA_UWSGI_CONF" "$NOVA_METADATA_UWSGI"
+
+    if [[ "$NOVA_BACKEND" == "LVM" ]]; then
+        clean_lvm_volume_group $DEFAULT_VOLUME_GROUP_NAME
+    fi
 }
 
 # configure_nova() - Set config files, create data dirs, etc
diff --git a/unstack.sh b/unstack.sh
index ccea0ef..cfbf22e 100755
--- a/unstack.sh
+++ b/unstack.sh
@@ -175,9 +175,5 @@
 # enabled backends. So if Cinder is enabled, and installed successfully we are
 # sure lvm2 (lvremove, /etc/lvm/lvm.conf, etc.) is here.
 if is_service_enabled cinder && is_package_installed lvm2; then
-    # Using /bin/true here indicates a BUG - maybe the
-    # DEFAULT_VOLUME_GROUP_NAME doesn't exist?  We should
-    # isolate this further down in lib/cinder cleanup.
-    clean_lvm_volume_group $DEFAULT_VOLUME_GROUP_NAME || /bin/true
     clean_lvm_filter
 fi