Tests end up leaving stale Dataflow jobs in apache-beam-testing project and exhaust GCP resources

Some tests (I'm not sure if this is the exhaustive list but they seem to appear in the dataflow console repeatedly) that seem to not be killed and eat our resources: 
 - test_reshuffle_preserves_timestamps (spotted multiple times in the dataflow console) (Python SDK)
 - test_flatten_same_pcollections (Python SDK)
 - testPairWithIndexWindowedTimestampedBounded (Java SDK)

 -  testPairWithIndexBasicBounded (Java SDK)
 
Temporary solution is to ignore them. Real solution requires greater investigation.

Please see the devlist thread for more context: https://lists.apache.org/thread.html/01eb33ae9c05d12bb0698f91adc0021662fdfe2978cfdfde28dc56b2%40%3Cdev.beam.apache.org%3E