[FLINK-21946] [table-planner-blink] FlinkRelMdUtil.numDistinctVals produces exceptional Double.NaN result when domainSize is in range(0,1)

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What is the purpose of the change

Fix Double.NaN result produced by FlinkRelMdUtil.numDistinctVals when domainSize is in range(0,1)

Brief change log

• add value check for FlinkRelMdUtil.numDistinctVals, entering old formula if matched

Verifying this change

Added ut & it case

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/Mesos, ZooKeeper: ( no )
• The S3 file system connector: ( no )

Documentation

• Does this pull request introduce a new feature? (no)

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Last check on commit ab18bbc (Wed Mar 24 09:22:04 UTC 2021)

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CI report:

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