[owners] Cache tree parse on public-facing status server endpoints (#494)
[owners] Cache tree parse on public-facing status server endpoints (#494)

* Use cached copy of parse tree on public endpoint

* Add comment and make refresh interval a constant

* Parse tree for first time after teams have been loaded

* Lint fixes

* Log startup of status server

ampproject/amp-github-apps,ampproject/amp-github-apps,ampproject/amp-github-apps,ampproject/amp-github-apps,ampproject/amp-github-apps