Update expiry of tab preview histograms

These histograms are still actively checked for two experiments.

Bug: 1144790
Change-Id: I2565d4a5df024c0da3a29c067c3bd34a6aa35f26
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2518701
Auto-Submit: Collin Baker <collinbaker@chromium.org>
Commit-Queue: Jesse Doherty <jwd@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#824424}

tools/metrics/histograms/histograms_xml/tab/histograms.xml

@@ -237,7 +237,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Tab.Preview.CaptureType" enum="TabPreviewCaptureType"
-    expires_after="2020-12-15">
+    expires_after="M92">
   <owner>dfried@chromium.org</owner>
   <owner>collinbaker@chromium.org</owner>
   <summary>Records how a tab preview image was generated.</summary>
@@ -265,7 +265,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Tab.Preview.TimeToFirstUsableFrameAfterStartCapture"
-    units="ms" expires_after="2020-12-15">
+    units="ms" expires_after="M92">
   <owner>dfried@chromium.org</owner>
   <owner>collinbaker@chromium.org</owner>
   <summary>
@@ -275,7 +275,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Tab.Preview.TimeToNotifyObserversAfterCaptureReceived"
-    units="microseconds" expires_after="2021-03-15">
+    units="microseconds" expires_after="M92">
   <owner>dfried@chromium.org</owner>
   <owner>collinbaker@chromium.org</owner>
   <summary>
@@ -289,7 +289,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Tab.Preview.TimeToStoreAfterFrameReceived"
-    units="microseconds" expires_after="2021-03-15">
+    units="microseconds" expires_after="M92">
   <owner>dfried@chromium.org</owner>
   <owner>collinbaker@chromium.org</owner>
   <summary>
@@ -301,7 +301,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Tab.Preview.TimeToStoreAfterTabSwitch" units="ms"
-    expires_after="2021-03-07">
+    expires_after="M92">
   <owner>dfried@chromium.org</owner>
   <owner>collinbaker@chromium.org</owner>
   <summary>
@@ -312,7 +312,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="Tab.Preview.VideoCaptureDuration" units="ms"
-    expires_after="M89">
+    expires_after="M92">
   <owner>dfried@chromium.org</owner>
   <owner>collinbaker@chromium.org</owner>
   <summary>