tests: Reduce the size of the test suite files

If we were to move to meson, the whole test suite would be available in
the dist, so make sure this doesn't balloon the size of the tarball.

Size reduction executed with:
for i in * ; do SIZE=$(stat --printf="%s" $i) ; if [ $SIZE -gt 131072 ] ; then dd if=$i of=$i.tmp bs=128k count=1 && mv $i.tmp $i ; fi ; done
1 job for wip/hadess/reduce-test-suite-size in 3 minutes and 51 seconds (queued for 1 second)