win: Let clang tot bots use the same test list as the main waterfall bots.

This ensures that the memory and clang tot bots run the same tests as the
main waterfall bots.

Everything running on the main waterfall must be tested with clang/tot too
to make sure compiler updates don't break anything. This change makes it
impossible for things to get out of sync (on win).

If https://chromium-review.googlesource.com/c/chromium/src/+/1088754 hadn't
been reverted, this would've been behavior-preserving. As-is, it adds
headless_browsertests and headless_unittests to the win clang tot bots.

Bug: 843511
Change-Id: I0c0568b47ca5ee56de7525bfcca8fc5e234acd6d
Reviewed-on: https://chromium-review.googlesource.com/1090818
Reviewed-by: Hans Wennborg <hans@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565258}
4 files changed