Filter schema in XDatabaseMetaData::getColumns so it would show correct
results in case there are more tables with the same name in different
schemas.

Change-Id: I8a986a43a8b049db3615d7ec2585ce68ebe3340e
Reviewed-on: https://gerrit.libreoffice.org/62696
Tested-by: Jenkins
Reviewed-by: Tamás Bunth <btomi96@gmail.com>