This method processes the provided requests to toggle the active status of the specified
split criteria setups. It returns a 207 Multi Status code on partial success or a 400 Bad Request status code if the
input is invalid.

Only the Active flag is changed; no other field on the split criteria setup is modified. A request is
rejected when the identifier does not exist, and also when the setup is already in the requested
state, since that would be a no-op.

Each response entry carries the index of the request it refers to, so results can be matched back to
the submitted requests.