Revert of Run mojo unit tests on the Android main waterfall. (patchset #2 id:20001...

Revert of Run mojo unit tests on the Android main waterfall. (patchset #2 id:20001 of https://codereview.chromium.org/1145343005/)

Reason for revert:
http://build.chromium.org/p/chromium.linux/builders/Android%20GN/builds/26585/steps/compile/logs/stdio#error1

ninja:error: unknown target 'html_viewer_unittests_apk'

Original issue's description:
> Run mojo unit tests on the Android main waterfall.
>
> Run Mojo additional unit tests on the "Android GN" bot:
> http://build.chromium.org/p/chromium.linux/builders/Android%20GN
> (No CQ yet; need Android GN testing support/devices there...)
> Add the necessary target mappings to ninja_to_gn.pyl
>
> Similar tests already run on Linux GN and our chromium.mojo FYI:
> http://build.chromium.org/p/chromium.linux/builders/Linux%20GN
> http://build.chromium.org/p/chromium.mojo/builders/Chromium%20Mojo%20Android
>
> BUG=478244,359249
> TEST=Steps run and pass on the bot.
> R=dpranke@chromium.org
>
> Committed: https://crrev.com/e1d8b35e1745d299ef346b1b6b6d116f417d2664
> Cr-Commit-Position: refs/heads/master@{#335112}

TBR=dpranke@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=478244,359249

Review URL: https://codereview.chromium.org/1177923004

Cr-Commit-Position: refs/heads/master@{#335117}