Beam examples failing for some runners: game_stats and leader_board

 Integration tests of examples: [game_stats](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/examples/complete/game/game_stats_it_test.py) and [leader_board](https://github.com/apache/beam/blob/master/sdks/python/apache_beam/examples/complete/game/leader_board_it_test.py) are failing for Spark, Flink, and Direct Runners with checksum error

 
```

AssertionError: Expected: (Test pipeline expected terminated in state: RUNNING and Expected checksum
is f3bc37a9581911f4288af5f3a70861d97265bf2f) but: Expected checksum is f3bc37a9581911f4288af5f3a70861d97265bf2f
Actual checksum is da39a3ee5e6b4b0d3255bfef95601890afd80709
```

The returning checksum for those failing tests is calculated from an empty array because the query doesn't match the expected results.

[https://ci-beam.apache.org/job/beam_PostCommit_Python_Examples_Direct/7/testReport/](https://ci-beam.apache.org/job/beam_PostCommit_Python_Examples_Direct/7/testReport/)

[https://ci-beam.apache.org/job/beam_PostCommit_Python_Examples_Spark/5/testReport/](https://ci-beam.apache.org/job/beam_PostCommit_Python_Examples_Spark/5/testReport/)

[https://ci-beam.apache.org/job/beam_PostCommit_Python_Examples_Flink/3/testReport/](https://ci-beam.apache.org/job/beam_PostCommit_Python_Examples_Flink/3/testReport/)

Those tests run successfully on Dataflow.

[https://ci-beam.apache.org/job/beam_PostCommit_Python_Examples_Dataflow/9/testReport/](https://ci-beam.apache.org/job/beam_PostCommit_Python_Examples_Dataflow/9/testReport/)

Imported from Jira [BEAM-13613](https://issues.apache.org/jira/browse/BEAM-13613). Original Jira may contain additional context.
Reported by: benglez.