[hotfix] Rename JobRestEndpointFactory to ApplicationRestEndpointFactory

[beliefer]

What is the purpose of the change

This PR aims to rename JobRestEndpointFactory to ApplicationRestEndpointFactory.
AFAIK, Flink already removed Job-Cluster or renamed it with Application-Cluster. There are many classes renamed from Job* to Application*. I guess we missing the JobRestEndpointFactory.

Brief change log

Rename JobRestEndpointFactory to ApplicationRestEndpointFactory.

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): (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:

• 4f90f5a Azure: SUCCESS

Bot commands

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

[beliefer]

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

[1996fanrui]

Thanks for the fix, LGTM

[beliefer]

@1996fanrui Thank you very much !