[FLINK-8249] [KinesisConnector] [hotfix] aws region is never setted in KinesisProducer

[eskabetxe]

What is the purpose of the change

solve the issue related, adding aws region to kinesis producer configuration

Verifying this change

This change added tests and can be verified as follows:

• Added test that validates that region is correctly setted

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

Documentation

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

[tzulitai]

Thanks for the fix @eskabetxe.
Can you squash commits fd9395f and 170372a, and rebase them onto latest release-1.4 branch?

[eskabetxe]

@tzulitai done on #5160

this could be closed

[tzulitai]

Thanks. @eskabetxe can you manually close this? Only the issuer of the PR can close it :)

[eskabetxe]

done