DPE-7726: Decrease waiting for DB connection timeout

We had to wait 30 seconds in case of lack of connection which is unnecessary long.

Also, add details for the reason of failed connection Retry/CannotConnect.

Author: taurus-forever

src/charm.py

@@ -2299,12 +2299,13 @@ def _can_connect_to_postgresql(self) -> bool:
         if not self.postgresql.password or not self.postgresql.current_host:
             return False
         try:
-            for attempt in Retrying(stop=stop_after_delay(30), wait=wait_fixed(3)):
+            for attempt in Retrying(stop=stop_after_delay(10), wait=wait_fixed(3)):
                 with attempt:
                     if not self.postgresql.get_postgresql_timezones():
+                        logger.debug("Cannot connect to database (CannotConnectError)")
                         raise CannotConnectError
         except RetryError:
-            logger.debug("Cannot connect to database")
+            logger.debug("Cannot connect to database (RetryError)")
             return False
         return True