validate: launcher: Initialize Test start time outside of wait_process

wait_process will be moved to TestManager, so the values used to track
process update must remain inside Test.

Patch 2/4 to make TestManager handle waiting for processes instead of
expecting each Test to do it.

validate/launcher/baseclasses.py

@@ -192,9 +192,6 @@ def get_current_value(self):
         return Result.NOT_RUN
 
     def wait_process(self):
-        self.last_val = 0
-        self.last_change_ts = time.time()
-        self.start_ts = time.time()
         while True:
             # Check process every second for timeout
             self.thread.join(1.0)
@@ -305,6 +302,10 @@ def run(self):
         self.thread = threading.Thread(target=self.thread_wrapper)
         self.thread.start()
 
+        self.last_val = 0
+        self.last_change_ts = time.time()
+        self.start_ts = time.time()
+
         try:
             self.wait_process()
         except KeyboardInterrupt: