[autotest] Also check server-side tests for inclusion in an ebuild.

We've now started packaging server-side tests, so it'd be kind for us to
notify a developer if they're about to try and enable a server-side test
to run, and we know that it won't.

BUG=chromium:217273
TEST=tried to add a server-side test not in ebuild to suite, upload failed
     tried to add a server-side test in an ebuild, upload succeeded

Change-Id: I865fa9bd4091ac82bd00eefe63a278fe65c9e529
Reviewed-on: https://chromium-review.googlesource.com/199373
Reviewed-by: Alex Miller <milleral@chromium.org>
Tested-by: Alex Miller <milleral@chromium.org>
Commit-Queue: Alex Miller <milleral@chromium.org>
1 file changed