Icinga DB Check: update not connected message

The check makes no attempt to explicitly connect to Redis, it uses the
connection of the IcingaDB feature, so this message better describes the state
in this situation.

lib/icingadb/icingadbchecktask.cpp

@@ -102,7 +102,7 @@ void IcingadbCheckTask::ScriptFunc(const Checkable::Ptr& checkable, const CheckR
 	auto redis (conn->GetConnection());
 
 	if (!redis || !redis->GetConnected()) {
-		ReportIcingadbCheck(checkable, commandObj, cr, "Icinga DB CRITICAL: Could not connect to Redis.", ServiceCritical);
+		ReportIcingadbCheck(checkable, commandObj, cr, "Icinga DB CRITICAL: Not connected to Redis.", ServiceCritical);
 		return;
 	}