fix(questdb): #678.4 distinguish cleared vs applied TTL log wording

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Historian.QuestDb/QuestDbSchemaBootstrapper.cs

@@ -137,7 +137,10 @@ internal sealed class QuestDbSchemaBootstrapper
             // The ALTER is a WAL transaction: tables() keeps the old value until it applies, so do NOT re-read to verify.
             await using (var alter = _conn.CreateCommand(conn, QuestDbTables.AlterTtl(table, _options.RetentionDays)))
                 await alter.ExecuteNonQueryAsync(ct).ConfigureAwait(false);
-            _log.LogInformation("Applied TTL {Days} day(s) to QuestDB table {Table}.", _options.RetentionDays, table);
+            if (_options.RetentionDays is { } days)
+                _log.LogInformation("Applied TTL {Days} day(s) to QuestDB table {Table}.", days, table);
+            else
+                _log.LogInformation("Cleared TTL on QuestDB table {Table}.", table);
         }
     }
 }