tests: don't log manifest-file in test-strip-cross.t
I'm confident that the file is there only to help produce a certain
manifest log; there is nothing special about the file's filelog
itself. (And there already is a `hg debugindex --manifest` call higher
up in the file that shows the crossed linkrevs.)
Differential Revision: https://phab.mercurial-scm.org/D6791
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ hg qsave
$ hg qrestore 2
restoring status: hg patches saved state