[FLINK-40301][table] Merge Calc nodes before ChangelogNormalize projection pushdown

[Au-Miner]

What is the purpose of the change

This change fixes an optimizer issue where adjacent Calc nodes created by watermark transposition prevent unused fields from being projected out on the input side of ChangelogNormalize. This unnecessarily increases the shuffle row width and ChangelogNormalize state size.

Brief change log

• Add FlinkCalcMergeRule.STREAM_PHYSICAL_INSTANCE to CHANGELOG_NORMALIZE_TRANSPOSE_RULES so that Calc nodes created by WatermarkAssignerChangelogNormalizeTransposeRule are merged before PushCalcPastChangelogNormalizeRule runs.
• Add testPushdownCalcNotAffectChangelogNormalizeKey2 to WatermarkAssignerChangelogNormalizeTransposeRuleTest.

Verifying this change

WatermarkAssignerChangelogNormalizeTransposeRuleTest#testPushdownCalcNotAffectChangelogNormalizeKey2 verifies that only the required field f and the ChangelogNormalize key a are projected to its input side. The rowtime field ingestion_time remains available to WatermarkAssigner without entering the shuffle or ChangelogNormalize state.

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:

• 3b6473a Azure: SUCCESS

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