from `message_format` and from `_message_read_dict_postprocess`.
The reading and initial formatting is done by `_message_read_dict_postprocess`,
which has been renamed more simply to `_message_format` due to its new goal.
This makes the methods easier to follow and does not increase the query count.
It actually reduces it when the data were already in the cache, by not always
reading them again.
Part of task-2180311
PR: #43841