CodeGenSettings: Set autoApply to false

Otherwise, the following assert is issued:
"!aspect->isAutoApply()" in [...]coreplugin/dialogs/ioptionspage.cpp:170

The assert appeared after pressing Apply button when
the Preferences... | C++ | Qt Class Generation tab was visible.

Change-Id: I6c5daf2a5f9f00c5edd7dca925447452bd9869bd
Reviewed-by: hjk <hjk@qt.io>

src/plugins/qtsupport/codegensettings.cpp

@@ -25,6 +25,7 @@ CodeGenSettings &codeGenSettings()
 
 CodeGenSettings::CodeGenSettings()
 {
+    setAutoApply(false);
     setSettingsGroup("FormClassWizardPage");
 
     embedding.setSettingsKey("Embedding");