fix: default to no expiration in SampleNagios

Author: itkovian

lib/vsc/utils/nagios.py

@@ -448,7 +448,7 @@ def __init__(self, **kwargs):
         self._final = None
         self._final_state = None
 
-        self._threshold = 0
+        self._threshold = None
         self._report_and_exit = False
 
         self._world_readable = False