Blender Git Loki

UI: remove button to enable auto-save after load factory preferences

Based on feedback from T66675, the current interface is confusing,
leading to users accidentally overwriting their preferences.

Now, once factory settings are loaded preferences are not saved
and the save button is shown (as when auto-save is disabled).

Tool tips note that factory settings require manual saving
afterwards.

Also rename preference menu items for better consistency
(settings/state -> preferences).