Revert "SLING-12427 - Stop using personal GitHub token for PR checks"

This reverts commit 2d2ec83d6848e7fa7ca44b8dd0cf147a74ea417b.

The token does not work as expected and cannot set the status.
diff --git a/vars/slingOsgiBundleBuild.groovy b/vars/slingOsgiBundleBuild.groovy
index 40dc443..2dd5540 100644
--- a/vars/slingOsgiBundleBuild.groovy
+++ b/vars/slingOsgiBundleBuild.groovy
@@ -13,7 +13,7 @@
         // maps values to node labels (available ones in https://cwiki.apache.org/confluence/x/ViZ4CQ)
         availableOperatingSystems : ['windows' : 'Windows', 'linux': 'ubuntu', 'linux-arm': 'arm', 'ubuntu': 'ubuntu'],
         mainNodeLabel : 'ubuntu',
-        githubCredentialsId: 'sling-github-token-asf'
+        githubCredentialsId: 'sling-github-token'
     ]
 
     def jobConfig = [