RemoteLinux: Proper double-remote

There seems something wrong with quoting the sed command for port
access which should be fixed independently.

As it is not crucial for plain deployment / run, make the test optional.

Change-Id: Id82bdc7c25a7fb6e2f8799676b869216a7720cfa
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/plugins/remotelinux/linuxdevicetester.cpp

@@ -154,9 +154,14 @@ TaskItem GenericLinuxDeviceTesterPrivate::gathererTask() const
         }
     };
     const auto error = [this](const DeviceUsedPortsGatherer &gatherer) {
-        emit q->errorMessage(Tr::tr("Error gathering ports: %1").arg(gatherer.errorString()) + '\n');
+        emit q->errorMessage(Tr::tr("Error gathering ports: %1").arg(gatherer.errorString()) + '\n'
+                           + Tr::tr("Some tools will not work out of the box.\n"));
+    };
+
+    return Group {
+        optional,
+        PortGatherer(setup, done, error)
     };
-    return PortGatherer(setup, done, error);
 }
 
 TaskItem GenericLinuxDeviceTesterPrivate::transferTask(FileTransferMethod method,