This is a regression from 2df0d9d3

Reverting it as the unitest from tdf#78907 still passes.
Besides, adding a new unittest for tdf#118702

Finally, adapt ooxmlexport9 and remove pointless assert which fails
with:

ooxmlexport9.cxx:557:Assertion
Test name: testBnc519228OddBreaks::Import_Export_Import
equality assertion failed
- Expected: <Any: (void)>
- Actual  : <Any: (string) Converted2>

Failures !!!
Run: 155   Failure total: 1   Failures: 1   Errors: 0


Change-Id: I486e9489ef6c3978cbcf90f3b9885248f4f92110
Reviewed-on: https://gerrit.libreoffice.org/57338
Tested-by: Jenkins
Reviewed-by: Justin Luth <justin_luth@sil.org>