Remove emeritus Linux sandbox owners.

The code review policy:
specifically prohibits emeritus.

https: //chromium.googlesource.com/chromium/src/+/master/docs/code_reviews.md
Change-Id: I345344d94f501364433d14284c72f73aab7cc3a8
Reviewed-on: https://chromium-review.googlesource.com/596676Reviewed-by: Matthew Dempsky <mdempsky@chromium.org>
Commit-Queue: Brett Wilson <brettw@chromium.org>
Cr-Commit-Position: refs/heads/master@{#491108}

sandbox/linux/OWNERS

@@ -2,9 +2,5 @@ jln@chromium.org
 jorgelo@chromium.org
 rsesek@chromium.org
 
-# Emeritus
-mdempsky@chromium.org
-rickyz@chromium.org
-
 # TEAM: security-dev@chromium.org
 # COMPONENT: Internals>Sandbox