Also check on mangled names when cleaning up the journal

Also check on mangled names when cleaning up the journal

Otherwise, after a first sync all the mangled entries would be removed
from the journal. On second sync it would be fine because we'd then have
seen the unmangled names because of the local files. Unfortunately
that'd mean reuploading them for nothing or trying to mkdir again on the
server for nothing... with a chance of using differently mangled names
(although I didn't spot it, I can't exclude it never happened).

This also led to weirdly getting stuck during sync when there was more
than one sync point.

Signed-off-by: Kevin Ottens <kevin.ottens@nextcloud.com>