Revert "Add partial Markdown for handling Timestamp block based on version (#…" (#7217)

This reverts commit 8acfcaf.

Author: DharmishthaVPatel

nservicebus/messaging/headers.md

@@ -17,13 +17,7 @@ The headers of a message are similar to HTTP headers and contain metadata about
 
 ## Timestamp format
 
-#if-version [8,)
-For all timestamp message headers, the format is `yyyy-MM-dd HH:mm:ss:ffffff Z` where the time is UTC. The helper class `DateTimeOffsetHelper` supports converting from UTC to wire format and vice versa by using the `ToWireFormattedString()` and `ToDateTimeOffset()` methods.
-#end-if
-
-#if-version [,8)
 For all timestamp message headers, the format is `yyyy-MM-dd HH:mm:ss:ffffff Z` where the time is UTC. The helper class `DateTimeExtensions` supports converting from UTC to wire format and vice versa by using the `ToWireFormattedString()` and `ToUtcDateTime()` methods.
-#end-if
 
 ### ISO 8601 format
 
@@ -48,30 +42,17 @@ Use the following code to generate or read the NServiceBus custom timestamp form
 ```cs
 const string Format = "yyyy-MM-dd HH:mm:ss:ffffff Z"; // Not ISO 8601
 
-#if-version [8,)
-public static string ToWireFormattedString(DateTimeOffset dateTime)
-{
-    return dateTime.ToUniversalTime().ToString(format, CultureInfo.InvariantCulture);
-}
-public static DateTimeOffset ToUtcDateTime(string wireFormattedString)
-{
-    return DateTimeOffset.ParseExact(wireFormattedString, Format, CultureInfo.InvariantCulture)
-       .ToUniversalTime();
-}
-#end-if
-
-#if-version [,8)
 public static string ToWireFormattedString(DateTime dateTime)
 {
     return dateTime.ToUniversalTime()
         .ToString(Format, CultureInfo.InvariantCulture);
 }
+
 public static DateTime ToUtcDateTime(string wireFormattedString)
 {
     return DateTime.ParseExact(wireFormattedString, Format, CultureInfo.InvariantCulture)
        .ToUniversalTime();
 }
-#end-if
 ```
 
 ## Transport headers