[BrowserSwitcher] Unify histograms expiry date

One of the histograms was expiring soon, and they all had different
expiry dates. Use the same expiry date for all BrowserSwitcher.*
histograms, to reduce maintenance burden.

Bug: 1138384
Change-Id: I8713ce8519e90faf1c690d0c83c7cf67910f87ec
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2514620
Commit-Queue: Nicolas Ouellet-Payeur <nicolaso@chromium.org>
Auto-Submit: Nicolas Ouellet-Payeur <nicolaso@chromium.org>
Reviewed-by: Robert Kaplow <rkaplow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825005}

tools/metrics/histograms/histograms_xml/browser/histograms.xml

@@ -660,7 +660,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.CacheFile.MkDirSuccess" enum="BooleanSuccess"
-    expires_after="2020-12-18">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -670,7 +670,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.CacheFile.MkTempSuccess" enum="BooleanSuccess"
-    expires_after="2020-12-18">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -681,7 +681,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.CacheFile.MoveSuccess" enum="BooleanSuccess"
-    expires_after="2020-12-18">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -693,7 +693,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.Decision" enum="BooleanBrowserSwitch"
-    expires_after="2021-05-02">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -705,7 +705,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.DecisionTime" units="ms"
-    expires_after="2021-05-02">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -716,7 +716,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.ExternalGreylistSize" units="rules"
-    expires_after="2020-12-18">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -726,7 +726,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.ExternalSitelistSize" units="rules"
-    expires_after="2021-03-21">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -736,7 +736,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.GreylistSize" units="rules"
-    expires_after="2020-12-18">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -746,7 +746,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.GreylistWildcard" enum="BooleanPresent"
-    expires_after="2020-12-18">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -757,7 +757,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.IeemSitelistSize" units="rules"
-    expires_after="2021-05-02">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -767,7 +767,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.LaunchSuccess" enum="BooleanSuccess"
-    expires_after="2020-11-15">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -777,7 +777,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.LaunchTime" units="ms"
-    expires_after="2021-04-11">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -787,7 +787,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.UrlListSize" units="rules"
-    expires_after="2020-12-18">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>
@@ -797,7 +797,7 @@ reviews. Googlers can read more about this at go/gwsq-gerrit.
 </histogram>
 
 <histogram name="BrowserSwitcher.UrlListWildcard" enum="BooleanPresent"
-    expires_after="2021-03-21">
+    expires_after="2021-04-04">
   <owner>nicolaso@chromium.org</owner>
   <owner>pastarmovj@chromium.org</owner>
   <summary>