[FLINK-38802][table] DDL with duplicated keys in table options should fail while validation

[snuyanzin]

What is the purpose of the change

To make the behavior more transparent ddl with duplicated keys in table options should fail rather than silently applying the last value e.g.

ALTER CATALOG cat SET ('K1' = 'V1', 'k2' = 'v2', 'k2' = 'another_value')

Brief change log

parseUtils and tests

Verifying this change

tests are introduced

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)
• If yes, how is the feature documented? (not applicable)

[flinkbot]

CI report:

• c23f4ff610a63c6f5a921346f08bea6ea284729a Azure: SUCCESS

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[snuyanzin]

looks like the initial behavior changed and it fails anyway, I submitted a PR to fix it and closing this one https://github.com/apache/flink/pull/27347