upload_manifest.py: Don't strip tests

Stripping tests breaks "make check":

  TEST tst-af-local-stripped.so OSv v0.05-386-gdf0fd92
  run_main(): cannot execute /tests/tst-af-local-stripped.so. Powering off.
  Test tst-af-local-stripped.so FAILED
  make: *** [check] Error 1

Fix the problem by not stripping tests.

Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>