Remove occurences of "../../ci-working-dir"

When I was running tests, they failed in an obscure way because they couldn't write to /home/tmp/ci-working-dir. It turns out this was because a chain of events starting at workspace.go:RootWorkingDirectory()

	dir = filepath.Join(folderPath, "..", "..", "ci-working-dir")

This escapes the temporary directory created by tests under /tmp and creates problems. There are many occurrences of "../../ci-working-dir" in both python and go code. We could replace all of them with a temporary directory under /tmp or /var/tmp or even at $HOME/ci-working-dir, or even require a command-line option.