[SAA] Remove unnecessary wss_server in favor of https_server

This makes it easier to write tests that rely on an iframe document and
a WebSocket connection being same-origin to each other.

Bug: 379030052
Change-Id: Id102927b903cafda551a4f849ee8ad8fbff2312c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6284966
Auto-Submit: Chris Fredrickson <cfredric@chromium.org>
Commit-Queue: Sandor «Alex» Major <sandormajor@chromium.org>
Reviewed-by: Sandor «Alex» Major <sandormajor@chromium.org>
Commit-Queue: Chris Fredrickson <cfredric@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1422341}