Add missing glance multi-store configurations

While removing registry [1] we by mistake removed some code related to
multiple store configuration for glance. This must be happened during
resolving merged conflicts.

Adding it back.

[1] https://review.opendev.org/708062

Change-Id: I2b84f7b7c51b7b20765a06b48c75006fd2e8ab71

lib/glance

@@ -143,6 +143,16 @@ function configure_glance {
     local dburl
     dburl=`database_connection_url glance`
 
+    # Configure multiple stores
+    if [[ "$GLANCE_ENABLE_MULTIPLE_STORES" == "True" ]]; then
+        local store enabled_backends
+        enabled_backends=""
+        for store in $(echo $GLANCE_MULTIPLE_FILE_STORES | tr "," "\n"); do
+            enabled_backends+="${store}:file,"
+        done
+        iniset $GLANCE_API_CONF DEFAULT enabled_backends ${enabled_backends::-1}
+    fi
+
     iniset $GLANCE_API_CONF DEFAULT debug $ENABLE_DEBUG_LOG_LEVEL
     iniset $GLANCE_API_CONF database connection $dburl
     iniset $GLANCE_API_CONF DEFAULT use_syslog $SYSLOG