Investigate impact and side-effects of bundling stax parser through CXF

See: REPO-1036
While the fix for REPO-1036 is fine (for now) as it only impacted SCXML tests output changes, bundling the stax parser seems to cause 'losing' some finer detail error reporting. It must be investigated in how much this also affects error reporting in production and/or if/how this might need to be improved or fixed otherwise.
For this also or even upgrading to a latest CXF might need to be considered and if the current solution for CMS7-8204 needs revisiting or further generalization.