Log repeated "no action" messages at a DEBUG level

Many people have to tune Patroni log level to WARNING, since messages like "no action: I am (patroni1), the leader with the lock" are emitted every HA loop run at an INFO level. Those are noisy and not terribly useful, as Patroni emits a different message anyway when the status quo changes.

This commit changes the default behavior by showing the "no action" message as an INFO for the first time, demoting subsequent repeated "no action" messages to DEBUG.

patroni/__main__.py

@@ -78,6 +78,8 @@ def __init__(self, config: 'Config') -> None:
         self.next_run = time.time()
         self.scheduled_restart: Dict[str, Any] = {}
 
+        self._last_cycle_info = ""
+
     def ensure_dcs_access(self, sleep_time: int = 5) -> 'Cluster':
         """Continuously attempt to retrieve cluster from DCS with delay.
 
@@ -209,7 +211,15 @@ def _run_cycle(self) -> None:
         the change and cache the new dynamic configuration values in ``patroni.dynamic.json`` file under Postgres data
         directory.
         """
-        logger.info(self.ha.run_cycle())
+
+        info: str = self.ha.run_cycle()
+        # if we report no action, show this message as INFO only when emitted for the first time
+        # demote it to DEBUG afterwards as long as it repeats
+        log_ha_action = logger.info
+        if info.startswith('no action.') or info.startswith('PAUSE: no action.') and self._last_cycle_info == info:
+            log_ha_action = logger.debug
+
+        log_ha_action(info)
 
         if self.dcs.cluster and self.dcs.cluster.config and self.dcs.cluster.config.data \
                 and self.config.set_dynamic_configuration(self.dcs.cluster.config):