systemd in rawhide now includes its own, minimal SNTP client. When chrony is installed and enabled this should have the effect of automatically turning off this minimal daemon. For this to work correctly, please add: Conflicts=systemd-timesyncd.service to chrony's [Unit] section.
Also see bug 1116370
On another thought, it seems strange to request that all services providing time synchronization should conflict with systemd-timesyncd. Beside chronyd and ntpd there are ptp4l, phc2sys, ptpd2 and possibly other services that would need to add that conflict. I think we should just make sure systemd-timesyncd is not enabled by default.