Apply conditional SET_SEMANTIC_TABLE trait to FROM_CHANGELOG

[raminqaf]

What is the purpose of the change

FROM_CHANGELOG is currently locked to row semantics — each row is processed independently, with no way to co-locate rows for the same key in the same parallel operator instance. This is fine for stateless downstreams but limits use cases where the resulting changelog feeds into a stateful operator keyed on the same column.

This PR uses the conditional-traits machinery introduced for TO_CHANGELOG in FLINK-39392 to switch FROM_CHANGELOG to set semantics when the call provides PARTITION BY. Behavior without PARTITION BY is unchanged.

-- Row semantics (unchanged)
SELECT * FROM FROM_CHANGELOG(input => TABLE cdc_stream);                                                                          
                                                                                                                                  
-- Set semantics: planner inserts Exchange(hash[id])                                                                              
SELECT * FROM FROM_CHANGELOG(input => TABLE cdc_stream PARTITION BY id);                                                          

Brief change log

• BuiltInFunctionDefinitions.FROM_CHANGELOG: input table argument adds withConditionalTrait(SET_SEMANTIC_TABLE, hasPartitionBy())
• Added a plan test (FromChangelogTest#testSetSemanticsWithPartitionBy) verifying the Exchange(hash[...]) propagation
• Added a semantic test program (FromChangelogTestPrograms#SET_SEMANTICS_PARTITION_BY) verifying end-to-end output equivalence
• Updated SQL reference docs (docs/.../changelog.md) and Table#fromChangelog JavaDoc

Verifying this change

This change added tests and can be verified as follows:

• FromChangelogTest#testSetSemanticsWithPartitionBy — plan test asserting the optimized rel plan contains Exchange(distribution=[hash[id]]) when PARTITION BY id is specified, and the output changelogMode propagates correctly
• FromChangelogSemanticTests (via SET_SEMANTICS_PARTITION_BY program) — end-to-end run verifying that adding PARTITION BY changes he parallel execution layout but does NOT alter row-level output (same +I, -U, +U, -D sequence as the row-semantics tests)
• All existing FromChangelogTest and FromChangelogSemanticTests cases continue to pass without modification, confirming the conditional trait does not regress the row-semantics path

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 (only FROM_CHANGELOG's declared traits change; the function signature and Table#fromChangelog API are unchanged)
• The serializers: no
• The runtime per-record code paths (performance sensitive): no (runtime function FromChangelogFunction is unchanged)
• 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? yes
• If yes, how is the feature documented? docs (docs/content/docs/sql/reference/queries/changelog.md) and JavaDocs
  (Table#fromChangelog)

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Was generative AI tooling used to co-author this PR?

• Yes (Claude Code / Opus 4.7)

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CI report:

• dbdf510 Azure: FAILURE

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