Revert "Remove custom signal handling in Triggerer (#23274)" (#24390)
Revert "Remove custom signal handling in Triggerer (#23274)" (#24390)

This reverts commit 6bdbed6c43df3c5473b168a75c50e0139cc13e88.
apache/airflow,nathanielvarona/airflow,Acehaidrey/incubator-airflow,nathanielvarona/airflow,cfei18/incubator-airflow,danielvdende/incubator-airflow,Acehaidrey/incubator-airflow,cfei18/incubator-airflow,nathanielvarona/airflow,Acehaidrey/incubator-airflow,danielvdende/incubator-airflow,apache/airflow,cfei18/incubator-airflow,danielvdende/incubator-airflow,danielvdende/incubator-airflow,nathanielvarona/airflow,cfei18/incubator-airflow,apache/airflow,Acehaidrey/incubator-airflow,apache/airflow,nathanielvarona/airflow,danielvdende/incubator-airflow,danielvdende/incubator-airflow,apache/airflow,apache/airflow,cfei18/incubator-airflow,Acehaidrey/incubator-airflow,nathanielvarona/airflow,Acehaidrey/incubator-airflow,cfei18/incubator-airflow