Consider adding deferrable support to SparkSubmitOperator #67168

Context

PR #67118 is attempting to add sync resumable support to SparkSubmitOperator via ResumableJobMixin. During review, @ashb suggested also supporting a deferrable=True mode in the same operator.

What this issue tracks

Add deferrable: bool = False parameter to SparkSubmitOperator:

• deferrable=False (default): sync path with ResumableJobMixin — worker slot occupied during polling, reconnects to existing driver on infrastructure failure (implemented in Add ResumableJobMixin with SparkSubmitOperator as a case study for surviving worker failures (standalone) #67118)
• deferrable=True: submit job, defer() to SparkDriverTrigger, worker slot freed during polling. When execute() is called again (only happens on user clear), resubmit fresh — no reconnect needed since crashes are handled by Trigger row persistence.

Relationship to #67118: The two modes share spark_job_id in task_state. A user can switch from sync to deferrable without any state migration.