We claim to have self-contained test cases, but the base_tests.sh script
still requires the WORKSPACE environment variable to be set outside of
the script, which is what Jenkins does.
This patch replaces WORKSPACE with a temporary directory and modifies
Jenkinsfile to use it when collecting logs.
Attempt to clarify the structure of our tests. Each test case is now
encapsulated in a script in `test/cases`. Each of these scripts should
be runnable on a pristine machine and be independent of each other. It
is up to the test-orchestractor to decide if they should be run
consequtively instance, or in parallel on separate instances. Each
script can execute several tests and call whatever helper binaries
is desired. However, each case should be assumed to always run as one.
