[FLINK-36755][yarn][k8s] Relax the limit about the pipeline.jar must have one in application mode

[fsk119]

What is the purpose of the change

Relax the limitation that application mode requires a main jar.

Brief change log

• Remove the check that pipeline.jar must have one jar

Verifying this change

This change added tests and can be verified as follows:

• Add tests to get packaged program if pipeline.jar is empty
• Add tests to deploy a cluster if pipeline.jar is empty

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

• Dependencies (does it add or upgrade a dependency): (yes / no)
• The public API, i.e., is any changed class annotated with @Public(Evolving): (yes / no)
• The serializers: (yes / no / don't know)
• The runtime per-record code paths (performance sensitive): (yes / no / don't know)
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (yes / no / don't know)
• The S3 file system connector: (yes / no / don't know)

Documentation

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

[flinkbot]

CI report:

• 9efb250 Azure: SUCCESS

Bot commands

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• @flinkbot run azure re-run the last Azure build

[davidradl]

@fsk119 I am unsure what problem this is fixing and what the motivation is behind this change.

[fsk119]

@davidradl Hi. Please read the FLIP about the change[1] or the PoC code[2]. This PR tries to relax the limit that user must upload a main jar to run the job in application mode. But it's not true for sql jobs because the main class is located at the job master.

[1] https://cwiki.apache.org/confluence/display/FLINK/FLIP-480%3A+Support+to+deploy+SQL+script+in+application+mode
[2] master...fsk119:flink:application-mode

[JunRuiLee]

Thanks @fsk119 for contributing. I've left a comment, PTAL.

[JunRuiLee]

LGTM