run-tests.sh: Timestamp each line of the logs
run-tests.sh: Timestamp each line of the logs

To help debug failures that only happen on CircleCI.

This uses `ts` from moreutils, which is already installed in our CI
docker image.

stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester,stb-tester/stb-tester