[FLINK-18399] [table-api-java] fix TableResult#print can not print the result of unbounded stream query

[godfreyhe]

What is the purpose of the change

In current implementation of PrintUtils, all result will be collected to local memory to compute column width first. this can works fine with batch query and bounded stream query. but for unbounded stream query, the result will be endless, so the result will be never printed. To solve this, we can use fix-length strategy, and print a row immediately once the row is accessed. This pr aims to fix the bug.

Brief change log

• [hotfix] correct the logic of truncateString method in PrintUtils
• Correct the logic of PrintUtils for unbounded stream query case

Verifying this change

This change added tests and can be verified as follows:

• Extended PrintUtilsTest and CliTableauResultViewTest to verify the fixes

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/Mesos, 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)

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Last check on commit 24a0d24 (Tue Jun 23 10:42:35 UTC 2020)

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[wuchong]

LGTM.

[wuchong]

Build is passed. Merging...