This prevents errors creating the attachment if a previous test
failed to delete it for some reason.
Change-Id: I2622d86e08987ad3ff201da84dc9ae210acf776d
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/2302722
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Joshua Peraza <jperaza@chromium.org>