[FLINK-37711] Remove unused getJobGraph from PipelineExecutorUtils

[beliefer]

What is the purpose of the change

This PR aims to remove unused getJobGraph from PipelineExecutorUtils.
The method getJobGraph in PipelineExecutorUtils is only used in test cases.
The client uses StreamGraph now. We should update these test cases.

Brief change log

Remove unused getJobGraph from PipelineExecutorUtils.

Verifying this change

This change is already covered by existing tests, such as (DefaultPackagedProgramRetrieverITCase).

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

• Dependencies (does it add or upgrade a dependency): (no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (no)
• 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, ZooKeeper: (no)
• The S3 file system connector: (no)

Documentation

• Does this pull request introduce a new feature? (no)

[flinkbot]

CI report:

• 7756521 Azure: SUCCESS

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[beliefer]

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[davidradl]

@beliefer could you go into a bit more detail in the jira as to why the Jobgraph is not used. I see it is used in a few places and is not deprecated.

[beliefer]

@beliefer could you go into a bit more detail in the jira as to why the Jobgraph is not used. I see it is used in a few places and is not deprecated.

Yes. Jobgraph is still used. I mean the method PipelineExecutorUtils.getJobGraph is not used anymore except some tests.

[beliefer]

ping @kl0u @wangyang0918 cc @1996fanrui @davidradl @GOODBOY008