LuaLS: Write settings after applying

Change-Id: I87cf48eee3c8df4481a672c31e6adf58ed1ec155
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/languageclient/lualanguageclient/lualanguageclient.cpp

@@ -313,10 +313,12 @@ public:
                         return s->m_id == m_clientSettingsId;
                     });
 
-                if (settings)
+                if (settings) {
                     LanguageClientManager::applySettings(settings);
-                else
+                    LanguageClientManager::writeSettings();
+                } else {
                     LanguageClientManager::applySettings();
+                }
             });
         }