Fix small cache test by returning original cache path

[sameluch]

Small test fix discovered while making the tests compatible with Azure Linux. This fixes out of space errors on later tests which are incompatible with the small_cache_path if this test is run.

[vmwclabot]

@sameluch, you must sign our contributor license agreement before your changes are merged. Click here to sign the agreement. If you are a VMware employee, read this for further instruction.

[vmwclabot]

@sameluch, we have received your signed contributor license agreement. The review is usually completed within a week, but may take longer under certain circumstances. Another comment will be added to the pull request to notify you when the merge can proceed.