Extend WebRTC AGC2 flag expiration and change owner

Bug: webrtc:7494
Change-Id: Ib75768a7fdc7c2c803b717f3f3c83ba8de45a74a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2351993Reviewed-by: Olga Sharonova <olka@chromium.org>
Commit-Queue: Ale Bzk <alessiob@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797217}

chrome/browser/flag-metadata.json

@@ -2304,8 +2304,8 @@
   },
   {
     "name": "enable-webrtc-hybrid-agc",
-    "owners": [ "aleloi" ],
-    "expiry_milestone": 83
+    "owners": [ "alessiob" ],
+    "expiry_milestone": 103
   },
   {
     "name": "enable-webrtc-new-encode-cpu-load-estimator",