OWNERS: Cleanup root owners file

Remove no-longer present files.
Expand kjellaner@ to own *.py in the root.

BUG=None
NOTRY=True

Review-Url: https://codereview.webrtc.org/2738993004
Cr-Commit-Position: refs/heads/master@{#17134}

OWNERS

@@ -6,11 +6,8 @@ tina.legrand@webrtc.org
 tommi@webrtc.org
 per-file .gitignore=*
 per-file .gn=kjellander@webrtc.org
-per-file *.gyp=*
+per-file *.py=kjellander@webrtc.org
 per-file AUTHORS=*
 per-file BUILD.gn=kjellander@webrtc.org
 per-file DEPS=*
-per-file PRESUBMIT.py=kjellander@webrtc.org
-per-file setup_links.py=*
-per-file sync_chromium.py=kjellander@webrtc.org
 per-file WATCHLISTS=*