Fix scheduler crash during 3.0 to 3.1 migration when retry_delay is None#56202

kaxil merged 5 commits intoapache:mainapache/airflow:mainfrom

dheerajturaga:bugfix/scheduler-crash-3_0-to-3_1dheerajturaga/airflow:bugfix/scheduler-crash-3_0-to-3_1Copy head branch name to clipboard