Extend UMA expiration of AdbSideloadingEnablingScreen for 1 year

We still need this data to keep track of feature use.  Extend for 1 year.

BUG=1138237
TEST=None

Change-Id: I27d5af9a309a8be6a44e1baeaf24dbe83b648d14
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2485612Reviewed-by: Jesse Doherty <jwd@chromium.org>
Commit-Queue: Victor Hsieh <victorhsieh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#818927}

tools/metrics/histograms/histograms_xml/arc/histograms.xml

@@ -66,7 +66,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Arc.AdbSideloadingEnablingScreen"
-    enum="AdbSideloadingPromptEvent" expires_after="M88">
+    enum="AdbSideloadingPromptEvent" expires_after="M96">
   <owner>victorhsieh@chromium.org</owner>
   <owner>tbuckley@chromium.org</owner>
   <summary>