Delay before the first re-drain of a ladder the cap above retired (#2975).
Retiring a ladder used to be final until an online event, so one chunk
fetch that stalled to give-up left a session that never went offline idle
at a coarser rung. The owning SceneLoader re-opens such ladders on an
exponential backoff instead: this delay, doubled per round, capped at
ABANDONED_RUNG_RETRY_MAX_MS, for at most
MAX_ABANDONED_RUNG_RETRY_ROUNDS rounds per view.
Delay before the first re-drain of a ladder the cap above retired (#2975). Retiring a ladder used to be final until an
onlineevent, so one chunk fetch that stalled to give-up left a session that never went offline idle at a coarser rung. The owning SceneLoader re-opens such ladders on an exponential backoff instead: this delay, doubled per round, capped at ABANDONED_RUNG_RETRY_MAX_MS, for at most MAX_ABANDONED_RUNG_RETRY_ROUNDS rounds per view.