[FLINK-38765] Fix persisted metadata handling in sink

[dawidwys]

What is the purpose of the change

Fixes a bug where an incorrect type is used in sink for

• shuffling
• sink upsert materializer
• constraint validation

Verifying this change

Added a test in SinkTestPrograms

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:

• b7ed906 Azure: FAILURE

Bot commands

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

[twalthr]

Is there no runtime change necessary?

[twalthr]

Thanks @dawidwys. +1 for this. Please update the release notes and let people know about the past inconsistency and that there is a potential restoring issue but the state was corrupted anyways.