AutoStandby: Always reschedule properly (#9258)

If we attempted to switch to standby with an upcoming task in the near future (< 3), we would forget to re-schedule the standby timer.

plugins/autosuspend.koplugin/main.lua

@@ -606,6 +606,10 @@ function AutoSuspend:AllowStandbyHandler()
         -- This shouldn't prevent us from actually consuming any pending input events first,
         -- because if we were woken up by user input, those events should already be in the evdev queue...
         UIManager:consumeInputEarlyAfterPM(true)
+    else
+        if not self.going_to_suspend then
+            self:_start_standby()
+        end
     end
 end