refactor: remove redundant SigInt handler

Since the Doist loop listens for the KeyboardInterrupt exception then it effectively handles the Ctrl-C SigInt interrupt already which means the shutdown handler only has to handle the SigTerm signal.

src/keria/app/serving.py

@@ -8,8 +8,8 @@
 class GracefulShutdownDoer(doing.Doer):
     """
     Shuts all Agency agents down before exiting the Doist loop, performing a graceful shutdown.
-    Sets up signal handlers in the Doer.enter lifecycle method and exits the Doist scheduler loop in Doer.exit
-    Checks for the signals in the Doer.recur lifecycle method.
+    Sets up signal handler in the Doer.enter lifecycle method and exits the Doist scheduler loop in Doer.exit
+    Checks for the shutdown flag being set in the Doer.recur lifecycle method.
     """
     def __init__(self, doist, agency, **kwa):
         """
@@ -29,11 +29,6 @@ def handle_sigterm(self, signum, frame):
         logger.info(f"Received SIGTERM, initiating graceful shutdown.")
         self.shutdown_received = True
 
-    def handle_sigint(self, signum, frame):
-        """Handler function for SIGINT"""
-        logger.info(f"Received SIGINT, initiating graceful shutdown.")
-        self.shutdown_received = True
-
     def shutdown_agents(self, agents):
         """Helper function to shut down the agents."""
         logger.info("Stopping %s agents", len(agents))
@@ -47,8 +42,7 @@ def enter(self):
         """
         # Register signal handler
         signal.signal(signal.SIGTERM, self.handle_sigterm)
-        signal.signal(signal.SIGINT, self.handle_sigint)
-        logger.info("Registered signal handlers for SIGTERM and SIGINT")
+        logger.info("Registered signal handlers for SIGTERM")
 
     def recur(self, tock=0.0):
         """Generator coroutine checking once per tock for shutdown flag"""