The LFS extension requires this, and if it isn't enabled on the client (or the
LFS extension isn't loaded), a web client gets a 500 instead of a sensible error
message.  Now it gets a different (client) error, but maybe it can be handled
more gracefully.  c0f11347b107 indicates that treemanifest repos have this issue
too.  29cfc474c5fd mentions gating this behind `experimental` so that the format
could change, but that was 7 years ago and we now have an experimental
`changegroup4` as well.

We can keep this as a config for the next cycle in case someone runs into an
unexpected problem, and then jettison it if the infinitepush bundle name changes
are either acceptable as-is or can be created differently.