The functionality to enroll a new node to a cluster was
introduced in #77292 as a CLI tool. This change replaces this
CLI tool with the option to trigger the enrollment functionality
on startup of elasticsearch via a named argument that can be
passed to the elasticsearch startup script (--enrollment-token)
so that the users that want to enroll a node to a cluster can do
this with one command instead of two.
In a followup PR we are introducing a CLI tool version of this
functionality, that can be used to reconfigure packaged
installations.
5d3b6bf2f7