[FLINK-16652][orc] BytesColumnVector should init buffer in Hive 3.x

[JingsongLi]

What is the purpose of the change

BytesColumnVector should init buffer before fill in Hive 3.x.
Otherwise there is a NPE.

Brief change log

For BytesColumnVector, initBuffer before init.

Verifying this change

TableEnvHiveConnectorTest#testDifferentFormats when hive 3.x

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)

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Last check on commit 7d54efd (Mon Mar 23 03:35:24 UTC 2020)

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[lirui-apache]

Thanks for fixing the issue. +1

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CI report:

• 7d54efd Travis: SUCCESS Azure: FAILURE

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