test:Folder tags shouldn't match after removal of file in given folder

Test for bug.  Current stemming support for notmuch adds extra terms
to the DB which aren't removed when the file renames are detected.

When folder tags are added to a message, Xapian terms for both XFOLDER
and ZXFOLDER are generated.  When one of the filenames are
renamed/removed, only the XFOLDER tags are removed, leaving it possible
for a match on a folder: tag that was previously but is no longer a
match in the maildir.
(cherry picked from commit 86e0baeb6df5509393832488c0de3520a1a5bdcb)