### JIRA - [x] My PR addresses the following [Airflow JIRA](https://issues.apache.org/jira/browse/AIRFLOW-2709) issues and references them in the PR title.
### Description - [x] This PR enhances the error handling in the Databricks hook (and in its corresponding operator). The PR adds the capability to wait between requests, and it adds support to handle a TEMPORARILY_UNAVAILABLE error. This error is neither a connection nor timeout error, and thus it is not correctly handled by the current hook implementation. ### Tests - [x] My PR adds a unit test to specifically test the new functionality in the hook, and modifies existing tests in the operator to ensure the hook is initialized correctly. [ Full content available at: https://github.com/apache/incubator-airflow/pull/3570 ] This message was relayed via gitbox.apache.org for [email protected]
