Reset everyone's duration time to classic (#8008)
Reset everyone's duration time to classic (#8008)

Reset unwanted migration of this setting to "modern"
done with #7897.
koreader/koreader,koreader/koreader,poire-z/koreader,NiLuJe/koreader,Frenzie/koreader,NiLuJe/koreader,Frenzie/koreader,poire-z/koreader