Shutdown global thread pool last (#3569)

Ha.shutdown() needs it to run some health checks

Ref #3526

Author: CyberDem0n

patroni/__main__.py

@@ -257,8 +257,6 @@ def _shutdown(self) -> None:
         """
         from patroni import thread_pool
 
-        thread_pool.get_executor().shutdown(wait=False)
-
         try:
             self.api.shutdown()
         except Exception:
@@ -268,6 +266,8 @@ def _shutdown(self) -> None:
         except Exception:
             logger.exception('Exception during Ha.shutdown')
 
+        thread_pool.get_executor().shutdown(wait=False)
+
 
 def patroni_main(configfile: str) -> None:
     """Configure and start ``patroni`` main daemon process.