[FLINK-10154] [kinesis connector] Make sure we always read at least one record in Kinesis Connector.

[jgrier]

What is the purpose of the change

Fixing a bug that can cause the Kinesis Connector to request zero records and therefore throw an exception.

Brief change log

One line fix to ensure a minimum Kinesis request size of 1 record.

Verifying this change

This change is a trivial rework / code cleanup without any test coverage.

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: 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

[bowenli86]

+1

[StefanRRichter]

LGTM 👍 Merging.