[NFC] - Try to work around failing tests

[demeritcowboy]

Overview

Some tests are failing on these, I think because the system temp dir is global to the test node, so if at some point in the past the test had left this folder around it would exist already when any test run comes along. So try to start from a clean slate.

[civibot]

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[eileenmcnaughton]

OK this seems to work & doesn't look like it will wipe my laptop hard drive

[demeritcowboy]

He he. Might give an excuse to get a new computer...