[AF] Extend histogram Autofill.ManageCardsPrompt expiry

Bug: 986495
Change-Id: I7dd05b34559aee36129a813993854cda37c54870
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1713944Reviewed-by: Brian White <bcwhite@chromium.org>
Commit-Queue: Jared Saul <jsaul@google.com>
Cr-Commit-Position: refs/heads/master@{#680033}

tools/metrics/histograms/histograms.xml

@@ -10161,10 +10161,9 @@ uploading your change for review.
 </histogram>
 
 <histogram name="Autofill.ManageCardsPrompt" enum="AutofillManageCardsPrompt"
-    expires_after="2019-09-01">
+    expires_after="2020-09-01">
   <owner>manasverma@google.com</owner>
   <owner>jsaul@google.com</owner>
-  <owner>sebsg@chromium.org</owner>
   <summary>
     The frequency of user interactions with the Manage Cards prompt.
   </summary>