Currently task queue statistics printing is handled by special methods when there is (supposedly) interest to do so.

This results in spotty tracing support: only a few task queue statistics are ever printed (for g1 and and parallel young gc).
Another side effect is that task queue statistics printing code is duplicated almost verbatim twice.

Put this code into GenericTaskQueueSet (or somewhere else central) so it can be used in all places (and the duplicate code removed).