Add engine flag support to Dataproc ClusterGenerator

[swainmoc]

BLOCKED ON : python client rollout

This change adds a 'engine' flag to the ClusterGenerator, allowing users to specify the engine during Dataproc cluster creation. This functionality is enabled by bumping the 'google-cloud-dataproc' pip package to version 5.27.0, which includes the necessary changes to support the new flag.

ClusterGenerator is an internal helper function that is used to generate cluster configs that is then used to pass to DataprocCreateClusterOperator dag (https://airflow.apache.org/docs/apache-airflow-providers-google/stable/operators/cloud/dataproc.html#generating-cluster-config)

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