Add gn_unittests to linux bots.

Note that this is adding them to the GYP-based builds, not the GN base builds.
That will come later.

R=brettw@chromium.org

Review URL: https://codereview.chromium.org/236743006

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@263751 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
Revert of add gn_unittests to linux bots (https://codereview.chromium.org/236743006/)

Reason for revert:
Fail on Linux Tests (dbg)(2)(32)
http://build.chromium.org/p/chromium.linux/builders/Linux%20Tests%20(dbg)(2)(32)
http://build.chromium.org/p/chromium.linux/builders/Linux%20Tests%20%28dbg%29%282%29%2832%29/builds/12079

Original issue's description:
> Add gn_unittests to linux bots.
> 
> Note that this is adding them to the GYP-based builds, not the GN base builds.
> That will come later.
> 
> R=brettw@chromium.org
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=263751

TBR=brettw@chromium.org,dpranke@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/237533005

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@263774 4ff67af0-8c30-449e-8e8b-ad334ec8d88c