Re-create the TestAPI object for each instance tested

This ensure we have clean stats for each rather than keeping data from
the previous run into the next one.

Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>

scripts/test_datagrepper_perfs.py

@@ -335,10 +335,7 @@ def main():
     test_time = 3600  # time in seconds, e.g. 36000
     ramp_up = 0  # total time in secs to ramp up. default 0, no wait
 
-    perf_test = TestAPI()
-    workers = []
     start_time = time.time()
-    perf_test.start_time = start_time
     print("Tests started at %s." % time.asctime())
 
     for env_name, base_url in [
@@ -347,6 +344,9 @@ def main():
         ("datagrepper-prod/aws", "http://datagrepper.arc.fedorainfracloud.org/datagrepper"),
         ("datagrepper-prod/openshift", "https://datagrepper-monitor-dashboard.app.os.fedoraproject.org"),
     ]:
+        perf_test = TestAPI()
+        perf_test.start_time = start_time
+        workers = []
 
         for i in range(concurrent_users):
             thread = Thread(