Push back expiry of some canvas histograms

We are still getting useful data from these. Pushing the deadline of
Canvas.TextMetrics.SetFont and OffscreenCanvas.TextMetrics.SetFont
by another year.

Bug: 1165020, 1160818

Change-Id: Ifa9124c3ceb383d5b15064c2eb8cb42443982339
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2622098Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Yi Xu <yiyix@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843111}

tools/metrics/histograms/histograms_xml/others/histograms.xml

@@ -1831,7 +1831,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Canvas.TextMetrics.SetFont" units="microseconds"
-    expires_after="M90">
+    expires_after="2022-01-31">
   <owner>yiyix@chromium.org</owner>
   <owner>fserb@chromium.org</owner>
   <summary>
@@ -10687,7 +10687,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="OffscreenCanvas.TextMetrics.SetFont" units="microseconds"
-    expires_after="2021-01-31">
+    expires_after="2022-01-31">
   <owner>yiyix@chromium.org</owner>
   <owner>fserb@chromium.org</owner>
   <summary>