[test] Fix test archive clobber.
[test] Fix test archive clobber.

The old version would always clobber.

NOTRY=true
NOTREECHECKS=true

Review URL: https://codereview.chromium.org/1177503005

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#28895}

UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh,UniversalFuture/moosh