Remove loose edges created during undo in dynamic-topology sculpt mode

Fixes [#34043] "Dyntopo: noise appear during sculpting (parasite edges)"
projects.blender.org/tracker/index.php?func=detail&aid=34043&group_id=9&atid=498

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54265 954f8c5b-7b00-dc11-b283-0030488c597c