ci: successful test retries evidently delete leftover tmpdir artifacts from previously failed runs

[Internal ref](https://cockroachlabs.slack.com/archives/CJ0H8Q97C/p1683725300749489).

This manifests as a failed tests saying you can find leftover test artifacts in some directory, when those artifacts cannot be found, specifically in cases where that test is successfully retried.

We do not have a root cause for this bug yet but my guess is that whatever code computes where these directories lives chooses the same directory for the re-run, and when the test succeeds those artifacts get wiped.

Jira issue: CRDB-27807