Remove javaLevel (#525)

Co-authored-by: Olivier Lamy <olamy@apache.org>

Author: basil

Jenkinsfile

@@ -1,5 +1,5 @@
 buildPlugin(configurations: [
     [ platform: "linux", jdk: "8"],
     [ platform: "windows", jdk: "8"],
-    [ platform: "linux", jdk: "11", javaLevel: "8" ]
+    [ platform: "linux", jdk: "11" ]
 ])