Fix test_suites.sh to fail if the chip-tool command fails.

If chip-tool crashed, the script was not treating this as a failure,
because the default exit code of a pipeline is that of the last
command in the pipeline and we are piping through tee.

scripts/tests/test_suites.sh

@@ -17,6 +17,8 @@
 #
 
 set -e
+set -o pipefail # Fail if anything in a pipeline fails, not just the last
+                # command which for us tends to be 'tee'.
 
 declare -i iterations=2
 declare -i delay=0