Related to #950
Using "DCEcomment-tracking" which has all active comment anchors, remove any anchors in the xml files that are not in use (this reflects the state of comments as of 2019-09-06, captured in an archived sheet of the spreadsheet in GD called "2019-09-08Tracking_ARCHIVE")
In oXygen, Xpath query used: //comment resulting list is in GD: "comment-anchors_20190906"