vertex ai training operators: add display_name to rendered fields

[WSHoekstra]

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Add display_name and model_display_name to list of rendered fields for Vertex AI operators.

[boring-cyborg]

Congratulations on your first Pull Request and welcome to the Apache Airflow community! If you have any issues or are unsure about any anything please check our Contributors' Guide (https:/apache/airflow/blob/main/contributing-docs/README.rst)
Here are some useful points:

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[potiuk]

For the future - you can add "Closes: #ISSUE_NUMBER" to the commit message and it will automatically link the issue you created and it will close it - saves a lot of duplicated effort.

Also - for such things we do not really need an issue - just open PR and add description what it does - we do not really like overhead and unnecessary beauracracy 😄

[shahar1]

Thanks for your contribution!
There was a static check error due to current limitations of the validate-operators-init static check: the templated fields should be defined in the constructor's signature and explicitly assigned via super().__init__(param=param, ...) or self.param = params - even in inherited classes.
I rebased and pushed the fix.

[boring-cyborg]

Awesome work, congrats on your first merged pull request! You are invited to check our Issue Tracker for additional contributions.