There is a keyword that allows us to break out of loops. Use it.
There's a small change in behaviour here: if we process multiple orphans
that are still orphans, then we'll only call mempool.check() once at the
end, instead of after processing each tx.
This is a backport of core#19498 [2/5]
https://github.com/bitcoin/bitcoin/pull/19498/commits/55c79a9cefb6c83cdebbf6c538c471607695b457
Depends on D10412