[JENKINS-71965] fix timezone in build history (#8800)

* [JENKINS-71965] fix timezone in build history

the timezone shown was always the daylight saving time when the users
selected timezone has daylight saving. The change will now consider the
actual timestamp of the build to determine if it was in daylight saving
time to properly calculate the timezone to show.

* make locale aware

core/src/main/java/hudson/Functions.java

@@ -692,13 +692,13 @@ public class Functions {
     }
 
     @Restricted(NoExternalUse.class)
-    public static String getUserTimeZonePostfix() {
+    public static String getUserTimeZonePostfix(Date date) {
         if (!isUserTimeZoneOverride()) {
             return "";
         }
 
         TimeZone tz = TimeZone.getTimeZone(getUserTimeZone());
-        return tz.getDisplayName(tz.observesDaylightTime(), TimeZone.SHORT);
+        return tz.getDisplayName(tz.inDaylightTime(date), TimeZone.SHORT, getCurrentLocale());
     }
 
     @Restricted(NoExternalUse.class)