Revert "Temp: use time.time instead of perf"

This reverts commit a4c3aea4.

tavern_time_request/request.py

@@ -2,7 +2,7 @@ import logging
 import requests
 from tavern.util import exceptions
 from tavern._plugins.rest.request import RestRequest
-import time
+from time import perf_counter as perf
 
 logger = logging.getLogger(__name__)
 
@@ -10,7 +10,7 @@ class HivemindRequest(RestRequest):
     def run(self):
         try:
             # add sent timestamp to each request in perf_counter format
-            start_time = time.time() * 1000.
+            start_time = perf()
             headers = self._request_args.get('headers', {})
             headers['Sent-At'] = str(start_time)
             self._request_args['headers'] = headers