> txmempool: have CompareTopologically sort missing txs first
>
> We use CompareTopologically to choose an order of txs to inv. Rather
> than sorting txs that have been evicted from the mempool at the end
> of the list, sort them at the beginning so they are removed from
> the queue immediately.
> net_processing: Boost inv trickle rate
>
> If transactions are being added to the mempool at a rate faster than
> INVENTORY_BROADCAST_MAX_PER_MB * BLOCK_SIZE_MB per second then peers'
> inventory_to_send queue can become relatively large. If this happens,
> increase the number of txids we include in an INV message by 5 for
> each 1000 txids in the queue.
>
> This will tend to clear a temporary excess out reasonably quickly; an
> excess of 4000 invs to send will be cleared down to 1000 in about 30
> minutes, while an excess of 20000 invs would be cleared down to 1000 in
> about 60 minutes.
This is a backport of core#27610