perf script - remove the internal usage of -t

removing the -t option that is being used on ab.  This is telling
ab to stop the scenario after 60 seconds; however, a test can run
much longer.

scripts/test/perf-load-katello.py

@@ -24,7 +24,7 @@ def randomString():
 
 def hit_url(hits, cookie, concurrency, url):
     #  ab  -n 10 -C "_src_session=BAh7CSIQX2NzcmZfW..snip..b9c7f05ccd78027" "http://0.0.0.0:3000/dashboard"
-    retval = os.system("ab -t 60 -n %s -C \"%s\" -c %s %s" % (hits, cookie, concurrency, url))
+    retval = os.system("ab -n %s -C \"%s\" -c %s %s" % (hits, cookie, concurrency, url))
 
 if __name__ == '__main__':