Clean up invalidation/OWNERS

- Add treib@ as new main POC while melandory@ is out.
- Remove (comment out) previous owner pavely@.
- Reduce duplication: Have chrome/browser/invalidation/OWNERS and
  ios/chrome/browser/invalidation/OWNERS refer to the "main" owners
  file instead of explicitly listing the same people.

Bug: none
Change-Id: I80524388818c26884c07928422b74d70e026076f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1913404
Commit-Queue: Marc Treib <treib@chromium.org>
Reviewed-by: Tatiana Gornak <melandory@chromium.org>
Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#715217}

chrome/browser/invalidation/OWNERS

-dcheng@chromium.org
-melandory@chromium.org
-nyquist@chromium.org
-pavely@chromium.org
+file://components/invalidation/OWNERS
 
 # COMPONENT: Services>Invalidation

components/invalidation/OWNERS

+melandory@chromium.org
+treib@chromium.org
+
+# Fallback owners, in case the above are unavailable:
 dcheng@chromium.org
 nyquist@chromium.org
-pavely@chromium.org
-melandory@chromium.org
+
+# Previous owner, can be added for historical context:
+# pavely@chromium.org
 
 # COMPONENT: Services>Invalidation
 # TEAM: chromium-reviews@chromium.org

ios/chrome/browser/invalidation/OWNERS

-dcheng@chromium.org
-melandory@chromium.org
-nyquist@chromium.org
-pavely@chromium.org
+file://components/invalidation/OWNERS
 
 # COMPONENT: Services>Invalidation