No need to loop over with pkill -f

I guess four times is better than one but if we need four times to kill
swift processes there is something pretty bad with it.

Change-Id: Id2ea2f4ca60feb9fddc7b3181063760d2044b421

lib/swift

@@ -657,10 +657,8 @@ function stop_swift() {
     if type -p swift-init >/dev/null; then
         swift-init --run-dir=${SWIFT_DATA_DIR}/run all stop || true
     fi
-    for type in proxy object container account; do
     # Dump all of the servers
     pkill -f swift-
-    done
 }
 
 # Restore xtrace