Updating Jenkins example DAGs to use XComArgs

[josh-fell]

Related to #10285

• Updated example DAG files such that xcom_pull() calls use an operator's .output property
• Added comments to which task dependencies, if any, are handled and/or created via XComArgs for transparency
• Removed or refactored the default_args pattern where necessary as requested by @ashb (i.e. removed a separated default_args declaration for deference for declaration as part of the DAG object)
• Other miscellaneous updates based on .output refactoring

Note: There are several instances where the xcom_pull() call was not updated. These instances involve accessing a specific value within the XCom or calling user-defined macros with an XCom value. Reference #16618 for an open issue to enhance the XComArg functionality to provide similar behavior as the classic xcom_pull() method.

Note: Not all DAGs were tested functionally (i.e. with hard integrations to source systems and executed), however each DAG was tested to compile and generate a DAG graph as expected locally.

An detailed summary of all changes made as part of this PR can be found below:

DAG File	Converted xcom_pull()?	Other Updates?	Comments
airflow/providers/jenkins/example_dags/example_jenkins_job_trigger.py	Yes	Yes	Removed explicit task dependencies that are created via XComArgs. Refactored grab_artifact_from_jenkins() function to take an input XComArgs from a previous task. Refactored default_args pattern.

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