[infra] Make infra tests idempotent

Change-Id: I1a75b211753ea5e097234dd4104d0906cfd04673
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/223916
Reviewed-by: Ben Wagner aka dogben <benjaminwagner@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
5 files changed