Move XIndexAccess Java tests to C++ for ScUniqueCellFormatsObj.

Change-Id: I2aabc835d37c5f12afacfcbafc2d7d6346619a3c
Reviewed-on: https://gerrit.libreoffice.org/64666
Tested-by: Jenkins
Reviewed-by: Jens Carl <j.carl43@gmx.de>