added: debug output to test.sh cleanup code

Changes to test.sh to incorporate conditional debug output in the cleanup code which has been causing pipeline failures. The debug output is turned on by setting the env var DEBUG to any value.

The pipeline clean job has been updated to turn on the debug output.

Note: the bash exit immediately switch needs to be disabled during the execution of the code in the cleanup() function so that the trap is not triggered and no debug output is displayed.