[session] cleanup session-time / cleanup-session-time... which are hard to grasp while there is no actual benefit to handle both. Now repo will close session without any activity since cleanup-session-time (24h by default), and the web authentication chain won't reconnect automatically anymore. I don't think there is a big deal in keeping repo session for such time. Also, ask the repo for latest session usage time, we can't know it for real on the web side (think of long running transactions). Closes #1083245.

option_group_changed('cleanup-session-time', 'web', 'main')