Remove smoke load test for Java and Python SDK

As discussed in PR: https://github.com/apache/beam/pull/11135#discussion_r392852028 

No one seems to use them and regular load test will fail too whenever something is wrong. There's plenty of load tests now and they are smaller than they used to be at the time of creating the smoke tests. If something is wrong there will be quite quick feedback from them. All that makes the smoke test redundant imo.