recover: only apply last journal record per file (issue6423)
This got broken in 2019 when the size check was introduced. It is most
noticable when dealing with transactions that involve an inline to
non-inline revlog storage transaction. It wasn't seen as much at the
time because the in-memory journal actually de-duplicated the entry
implicity, but since 63edc384d3b7 the on-disk journal is used for
rollback as well as recover.
Differential Revision: https://phab.mercurial-scm.org/D10726