[FLINK-22619][python] Drop usages of BatchTableEnvironment and old planner in Python

[twalthr]

What is the purpose of the change

This is a major cleanup of the Python module that drops support for BatchTableEnvironment and old planner.

Some tests might need to be reintroduced in followup issues. We might need several cleanup iterations to make the API clean and concise again. Also the documentation.

Brief change log

Removes usages of:

• DataSet
• BatchTableEnvironment
• Legacy planner
• ExecutionEnvironment

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): yes
• The public API, i.e., is any changed class annotated with @Public(Evolving): yes
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn/Mesos, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not applicable

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Last check on commit 881ebf0 (Sat Aug 28 12:13:01 UTC 2021)

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[twalthr]

CC @dianfu @HuangXingBo
I'm sure I forgot something. Feel free to push commits to this pull request if you think some tests should remain in a modified version. My Python deletion skills are better than my Python programming skills ;-) Also the Python shell needs an update as it does not use the unified TableEnvironment yet.

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CI report:

• 881ebf0 Azure: SUCCESS

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[HuangXingBo]

@twalthr Thanks a lot for the work. I will take a look asap.

[HuangXingBo]

Hi @twalthr I have pushed two commits about reverting some python tests and removing python serializers used in old planner.

[twalthr]

Thanks for the additional commits @HuangXingBo. I'm fine to merge this PR now once the build turns green. Are you also giving your ok or are we expecting another review?

[HuangXingBo]

LGTM.