The main problem was that UserInstallation did not point to the usual
workdir/unittest/, so initialization failed early, not finding the
soffice.cfg directory under
workdir/CppunitTest/libreofficekit_tiledrendering.test.user/.

Disable one testcase that still fails, though.

Change-Id: I3fdae5ead47dd2a805a0ed8d3cb407938f868e3b