Problem/Motivation
See #3463225: Prevent 'downgrades' from maintenance minors to older minor releases for the next major version for background.
If we add a hook_update_N() to system module in 11.1, and backport this to 10.4 using the equivalent updates API, then a site that attempts to 10.4.0 to 11.0.0 will get a requirements error that they're trying to update to a release that is too old, and they should update to a newer release instead (e.g. 11.1).
We don't currently have such an update, so the idea here is to add an empty/no-op update purely to prevent unintentional downgrades like the above from happening.