Adjust OWNERS for //testing.

We used to have a wildcard OWNERS entry for //testing, and so
some of the sub-directories had "set noparent" directives.

The wildcard is now gone, so this CL removes the "set noparent"
and updates comments to be a bit clearer.

R=phajdan.jr@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1415633004

Cr-Commit-Position: refs/heads/master@{#358742}
2 files changed