Plugins: Don't exclude allowed plugins from available plugins list

This fixes issue that the allowed plugin (enabled by user) would
disappear from the all plugins list (in preferences) after failing
to load on startup.

src/lib/plugins/plugins.cpp

@@ -180,9 +180,6 @@ void Plugins::loadAvailablePlugins()
         QDir pluginsDir = QDir(dir);
         foreach (const QString &fileName, pluginsDir.entryList(QDir::Files)) {
             const QString absolutePath = pluginsDir.absoluteFilePath(fileName);
-            if (m_allowedPlugins.contains(absolutePath)) {
-                continue;
-            }
 
             QPluginLoader* loader = new QPluginLoader(absolutePath);
             PluginInterface* iPlugin = qobject_cast<PluginInterface*>(loader->instance());