Over time the size of our junit xml has exploded to the point where
test-grid fails to process them. We still have the original/full
*.stdout files from where the junit xml files are generated from so the
junit xml files need NOT have the fill/exact output for
processing/display. So let us prune the large messages with an
indicator that we have "[... clipped...]" some of the content so folks
can see that they have to consult the full *.stdout files.
Signed-off-by: Davanum Srinivas <davanum@gmail.com>