`org.jenkinsci.plugins.durabletask.BourneShellScriptTest` is too unstable

[basil]

In this repository, we set surefire.rerunFailingTestsCount=4 to run failing tests up to 4 times, and we also have a retry(2) block in the Jenkinsfile. A test that manages to fail despite all of this is too flaky to be included in the suite. We recently excluded org.jenkinsci.plugins.durabletask.BourneShellScriptTest from the suite because it was causing too many problems for unrelated PRs. We should try re-enabling that test in a new PR and investigate how to get it to pass reliably again.

[jglick]

CC @car-roll