Can iOS be configured so apps do not create screenshots when the app suspends?
There's no global switch in iOS 9 or earlier. The app developers can decide, what the app show during loading. 

If you see security issues or just feel that the experience using this feature is poor, the only remedy today is to contact the developer. Many professional apps like 1Password and Apple notes are coded to not disclose secure information in a temporary app image. 

Another option would to be to send feedback to Apple or a bug report detailing any lapses or explaining how this should be an optional control. Apple could change this in future OS if a case were made well enough or by enough people.