heartbeat: remove w2008 in the CI

Win2k8 was already old when heartbeat was created

It's quite unusual to put heartbeat on a 'legacy' machine

We've never heard of anyone using heartbeat+win2k8

The win2k8 tests are flaky

heartbeat/Jenkinsfile.yml

@@ -79,11 +79,6 @@ stages:
         platforms:             ## override default labels in this specific stage.
             - "windows-10"
         stage: extended
-    windows-2008:
-        mage: "mage build unitTest"
-        platforms:             ## override default labels in this specific stage.
-            - "windows-2008-r2"
-        stage: extended
     windows-8:
         mage: "mage build unitTest"
         platforms:             ## override default labels in this specific stage.