Enable the new test launcher for sandbox_linux_unittests

BUG=355084, 236893
R=jln@chromium.org

Review URL: https://codereview.chromium.org/221873004

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@263213 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
Remove a few dead MSVS_VERSION checks.

We only support 2013.

TBR=robertshield@chromium.org
BUG=340358

Review URL: https://codereview.chromium.org/233843003

git-svn-id: http://src.chromium.org/chrome/trunk/src/testing@263460 4ff67af0-8c30-449e-8e8b-ad334ec8d88c