Get rid of testlistjson query parameter.

This is an optimization to make it so that we don't have to send
the whole results.json file down since the JSONResultsGenerator
needs this to figure out which tests it can strip. The only code
left that uses this is the Android fork of this code, which needs
to go away. So, I'm not OK with keeping this special-cased code
in the generic test results server just for that.

Deleting the code means that the requests will get the full
results.json file instead of the one with the results and times
stripped out.

TBR because this is causing 500s on the live server and that
push can't be rolled back without breaking other things.

TBR=szager@chromium.org

Review URL: https://codereview.chromium.org/463683002

git-svn-id: svn://svn.chromium.org/blink/trunk@180005 bbb929c8-8fbe-4397-9dbb-9b2b20218538