suite: Terminate processes in LIFO order

Usually the first process we started is the one we want to stay until
the end.

Change-Id: I08ea01a42af68191a659fdf8173e3fec9b1e1cfd

src/osmo_gsm_tester/suite.py

@@ -214,7 +214,7 @@ class SuiteRun(log.Origin):
     def remember_to_stop(self, process):
         if self._processes is None:
             self._processes = []
-        self._processes.append(process)
+        self._processes.insert(0, process)
 
     def stop_processes(self):
         if not self._processes: