autotest: Fix site_wifitest based tests

When the wifi testbed configuration files were removed, site_wifitest
began to fail because it was unable to open those files (despite the
file not actually being used for anything).

BUG=None
TEST=network_WiFiManager tests pass again.

Change-Id: Ia39eebbb30bdccb65cb626d4cf454947c15f18b5
Reviewed-on: https://chromium-review.googlesource.com/176059
Tested-by: Christopher Wiley <wiley@chromium.org>
Reviewed-by: Paul Stewart <pstew@chromium.org>
Commit-Queue: Christopher Wiley <wiley@chromium.org>
1 file changed