test for tdf#34957: change font in test document to make it work here

Previously the text was too long, ending on second page,
and table was on third page here, but is expected on second.
Change font to 'Liberation Serif' which seems to be used elsewhere,
and set line spacing to 'single' which makes the test succeed.

Change-Id: I4fc903c5d83308608e70e3e440d5277abd487052