DOCX import: close rPrChange properly.

Call endtrackchanges when rPrChange ends so the
corresponding redline will be removed.

(cherry picked from commit 75e7d6f12e914b63e66968890533b2a56d0b1a7e)

Conflicts:
	sw/qa/extras/ooxmlimport/ooxmlimport.cxx
Reviewed on:
	https://gerrit.libreoffice.org/7195

Change-Id: I4091d7b54e0a74f3158cc979f210577a2dc29783