Summary
-------

Obsolete the `GCTaskTimeStampEntries` command line option.

Problem
-------
The change JDK-8204951 modified Parallel GC to use the same abstraction for parallel worker threads as other garbage collectors. This flag enabled specific logging for the old abstraction which does not exist any more.

Solution
--------

Directly obsolete the `GCTaskTimeStampEntries` option now as the functionality is not available any more. 

Specification
-------------

```
diff --git a/src/hotspot/share/runtime/arguments.cpp b/src/hotspot/share/runtime/arguments.cpp
index 78d865d04a8..acd42ba5ec0 100644
--- a/src/hotspot/share/runtime/arguments.cpp
+++ b/src/hotspot/share/runtime/arguments.cpp
@@ -622,6 +622,7 @@ static SpecialFlag const special_jvm_flags[] = {
   { "GCLockerInvokesConcurrent",     JDK_Version::undefined(), JDK_Version::jdk(14), JDK_Version::jdk(15) },
   { "BindGCTaskThreadsToCPUs",       JDK_Version::undefined(), JDK_Version::jdk(14), JDK_Version::jdk(16) },
   { "UseGCTaskAffinity",             JDK_Version::undefined(), JDK_Version::jdk(14), JDK_Version::jdk(16) },
+  { "GCTaskTimeStampEntries",        JDK_Version::undefined(), JDK_Version::jdk(14), JDK_Version::jdk(16) },
 
 #ifdef TEST_VERIFY_SPECIAL_JVM_FLAGS
   // These entries will generate build errors.  Their purpose is to test the macros.
```