Revert of Mark ui_base_unittests target to be used on Swarming. (patchset #2 id:20001 of https://codereview.chromium.org/1063603002/)

Reason for revert:
Turns "isolate tests" red on some bots, reverting while maruel investigates: http://build.chromium.org/p/chromium.fyi/builders/CrWinClang%28dbg%29/builds/765/steps/isolate%20tests/logs/stdio

Original issue's description:
> Mark ui_base_unittests target to be used on Swarming.
>
> Patch generated with the following command line:
>
> $ ./testing/buildbot/manage.py --convert ui_base_unittests
>
> BUG=98637
> TEST=trybots?
> R=maruel@chromium.org
>
> Committed: https://crrev.com/79e2c2139c83ccc50de4a73288eac94ab13b94f0
> Cr-Commit-Position: refs/heads/master@{#333991}

TBR=maruel@chromium.org,tfarina@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=98637

Review URL: https://codereview.chromium.org/1179083002

Cr-Commit-Position: refs/heads/master@{#334051}
7 files changed