internal/frontend: fix broken test for TestServer/search
internal/frontend: fix broken test for TestServer/search

This fixes a test that was broken in commit
be7963c72f1b33c28a4af1e7d3ddf4493f7508cc.

Change-Id: I66befcce60b62b7b154e946a845e1c360f17ccc6
Reviewed-on: https://team-review.git.corp.google.com/c/golang/discovery/+/596645
Reviewed-by: Robert Findley <9179eee875d1ee628c37fb47d7e749e855ffd21f@google.com>
CI-Result: Cloud Build <ea5729d4cf3392b9d382b6ca272c65aa27554f44@system.gserviceaccount.com>

golang/pkgsite,golang/pkgsite,golang/pkgsite,golang/pkgsite