live: use legacy backup image suffix

Image backup is considered a legacy feature. Use the legacy mechanism of
naming image backups by adding ".ant" suffix.

Previously, by using the strftime suffix clients were reporting that the
disk were getting full rather quickly.

When a good method for image deletion is implemented then a proper
backup naming mechanism should be reconsidered.

src/live/ogOperations.py

@@ -450,8 +450,7 @@ class OgLiveOperations:
             logfile = open('/tmp/command.log', 'wb', 0)
 
             if os.path.exists(image_path) and backup:
-                    now = datetime.datetime.now().strftime("%Y_%m_%d_%H_%M_%S")
-                    shutil.move(image_path, f'{image_path}_{now}')
+                    shutil.move(image_path, f'{image_path}.ant')
 
             p1 = Popen(cmd1, stdout=PIPE, stderr=logfile)
             p2 = Popen(cmd2, stdin=p1.stdout)