LogCleaner CleanerStats swap logic seems incorrect

In LogCleaner, we keep track of two instances of the CleanerStats object in a tuple object. One instance is intended to keep track the stats for the last cycle while the other is for the current cycle. The idea is to swap them after each cleaning cycle, but the current logic does not actually mutate the existing tuple, which means that we always clear the same instance of CleanerStats after each cleaning.