Rename existing iOS Simulator bots to match the new one. Buildbot changes: https://chromium-review.googlesource.com/423055 BUG=chromium:677385 TBR=ehmaldonado@webrtc.org Review-Url: https://codereview.webrtc.org/2601353003 . Cr-Commit-Position: refs/heads/master@{#15842}