[Python/tornado] add integration tests and fix bugs (#6925)

* tests: add integration test for python-tornado

* [python-tornado-client] tests: increase timeout for test_upload_file

* [python-tornado-client] fix: tornado client passes tests

samples/client/petstore/python-tornado/tests/util.py

@@ -0,0 +1,8 @@
+# flake8: noqa
+
+import random
+
+
+def id_gen(bits=32):
+    """ Returns a n-bit randomly generated int """
+    return int(random.getrandbits(bits))