Fix devstack cleanup when using amphorav2

When cleaning up a devstack environment with amphorav2 enabled,
./clean.sh might fail because redis has already been stopped and
uninstalled.
This commit move the stop_redis step to the octavia_stop step and
ensures that stopping redis doesn't fail.

Change-Id: I987535e90cbf13917c50c5905c64b614188928ec
(cherry picked from commit 5d470357ec)
(cherry picked from commit 168f1a1212)
(cherry picked from commit 5d49484eb6)

devstack/plugin.sh

@@ -249,6 +249,10 @@ function install_redis {
     pip_install_gr redis
 }
 
+function stop_redis {
+    stop_service redis || true
+}
+
 function uninstall_redis {
     if is_fedora; then
         uninstall_package redis
@@ -258,8 +262,6 @@ function uninstall_redis {
         uninstall_package redis
     fi
 
-    stop_service redis
-
     pip_unistall redis
 }
 
@@ -629,6 +631,10 @@ function octavia_stop {
     else
         die "Unknown network controller. Please define octavia_delete_network_interface_device"
     fi
+
+    if [[ ${OCTAVIA_ENABLE_AMPHORAV2_PROVIDER} == True ]]; then
+        stop_redis
+    fi
 }
 
 function octavia_cleanup {