Adding a note to 'test_update_user_password' test for Keystone V2

A note with time.sleep(1) were added for consistency like it is done
for the corresponding tests in [1]. Also, a few typos were fixed and
weird self.assertEqual(...)

    subject_token = resp['x-subject-token']
    ...
    self.assertEqual(resp['x-subject-token'], subject_token)

was deleted.

[1] https://review.openstack.org/#/c/275497/

Change-Id: I9cdd49a5361e21205a470da21d5cf69ce5b464bf
4 files changed