Switch blink to *_blink_rel bots again.

This time they're SVN based. They seem to be behaving properly.

TBR=eseidel@chromium.org
BUG=238381

Review URL: https://codereview.chromium.org/20618003

git-svn-id: svn://svn.chromium.org/blink/trunk@155062 bbb929c8-8fbe-4397-9dbb-9b2b20218538