Traverse pipeline topology looking for the flow control stuck vunerability

[FelonEkonom]

Every randomized time interval check if there is a diamond structure in the pipeline topology with a root having :auto flow control and pull effective flow control (and proper flow control on both paths to the "leaf").

If it occurs, add a debug/warning log informing about possibility of getting stuck, if the data will be unbalanced and possible solutions (setting auto_demand_size to a bigger number, modifying pipeline topology).

Another possible approach is to auto-magically-bump auto_demand_size in case of getting stuck