You should not be disabling auto update on Xcode or attempting version control of Xcode. If your developers are having issues staying current, they should be reaching out to Apple using their Developer account.
Xcode is an AppStore App, JAMF can tell Macs to update AppStore apps at a given interval. You can stop JAMF from telling Xcode to update with API commands in the Mac App Policy. However, the Mac will still parodically check for updates and do its own thing. I'm not sure if you can defer Xcode updates with Defer update of "Applications and non-OS updates", but if it does work that will give you up to an additional 90 days.
