Extend validity of WebRTC.Audio.AudioInterruptionMs to 1 year from now

This is a useful metric that is in active use.

Change-Id: I2d8cacbe5aa1fe30ffa71826841d18342d4f4695
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2558417Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Brian White <bcwhite@chromium.org>
Auto-Submit: Ivo Creusen <ivoc@chromium.org>
Cr-Commit-Position: refs/heads/master@{#830709}

tools/metrics/histograms/histograms_xml/web_rtc/histograms.xml

@@ -227,7 +227,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="WebRTC.Audio.AudioInterruptionMs" units="ms"
-    expires_after="2021-01-03">
+    expires_after="2021-11-23">
   <owner>hlundin@chromium.org</owner>
   <owner>ivoc@chromium.org</owner>
   <summary>