Require someone working on PlzNavigate to approve changes to the test filters.

Since PlzNavigate is close to launching, we want to ensure that someone from the team approves any new additions to the test filters for browser_tests & content_browsertests, which are almost empty now.

BUG=368813

Review-Url: https://codereview.chromium.org/2548363003
Cr-Commit-Position: refs/heads/master@{#436398}
1 file changed