Added dagrun clear command to airflowctl

[justinpakzad]

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Added dagrun clear command to airflowctl. Updated the DagRunOperations class with a new clear() method. The dry_run and only_failed parameters default to None and if not provided are assigned True and False respectively, matching the API's defaults. This is needed because CommandFactory sets all boolean default values to None anyways.

Added two additional unit tests for both dry run and non dry run clearing and added the new command to the integration tests. I also tested this locally by clearing actual Dag runs and it's working as expected.

Was generative AI tooling used to co-author this PR?

• Yes (Claude Opus 4.6)

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• For fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
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[justinpakzad]

I think there was an issue fetching the Docker image for the CTL integration tests. If someone could re-trigger it that would be great. Thanks.