Set fuchsia fyi bot to build //v8:d8 as well

(Also base_unittests, which is removed from build repo config in https://chromium-review.googlesource.com/c/530188/ )

BUG=707029, 731217

Review-Url: https://codereview.chromium.org/2930193002
Cr-Commit-Position: refs/heads/master@{#478530}