The bug was caused because the ScriptService had no reference to a ClusterState instance,
because it received the ClusterState after the PipelineStore. This only is the case
after a restart.
A bad side effect is that during a restart, any pipeline to be loaded after the pipeline that uses a stored script,
was never loaded, which caused many pipeline to be missing in bulk / index request api calls.
This is related to #27933. It introduces a jar named elasticsearch-core
in the lib directory. This commit moves the JarHell class from server to
elasticsearch-core. Additionally, PathUtils and some of Loggers are
moved as JarHell depends on them.