[photonlibpy] stop getting full stack trace on test failure (#1568)

Signal/noise ratio is too low with this enabled. When dealing with #1567
I got ~46000 lines of errors going around in a circle rather than just
an import failure at the scope of each failed test

photon-lib/py/buildAndTest.sh

@@ -11,4 +11,4 @@ for f in dist/*.whl; do
 done
 
 # Run the test suite
-pytest -rP --full-trace
+pytest -rP