[applets/batterymonitor] Fix it, pt.4: Nuke a truly horrible layout HACK
GridLayout no longer crashes was described in an old comment and nowadays is pretty safe to use. Repeater, however, still doesn't support instantiating multiple top-level items at once, which is unfortunate but can be worked around; see upstream Qt bug below.
In this case, however, simple is better than smart-ish; the entire at-most-two-rows table-like grid can be recreated entirely without Repeaters and clever models. Just do it.
See also: QTBUG-38098
Gimme an hour, and I'll take you two whole months.