[batterytracker] Do not shutdown while in charger level drops from 2% to 1%

We had logic that if in USER state battery level continued dropping even phone was connected to charger, we did shutdown. This PR removes that logic because it turned out not to be that useful. We still do shutdown when battery level reaches 0% while charger is connected.

Signed-off-by: Pekka Lundstrom <pekka.lundstrom@jollamobile.com>