This commit introduces auto-configuration for the new Elasticsearch
clients that are based upon their new Java client. The new Java
client builds on top of their existing low-level REST client,
replacing the high-level REST client which has been deprecated.
As part of introducing support for the new Elasticsearch client,
the auto-configuration for the templates (both imperative and
reactive) provided by Spring Data has also been updated to use the
new templates that build upon the new Java client.
As part of these changes, support for the high-level REST client and
the old Spring Data Elasticsearch templates has been removed. One
significant change is that the new reactive template is no longer
based on WebClient. As a result, the WebClient-specific configuration
property has been removed.
Closes gh-30647
Closes gh-28597
Closes gh-31755
5c057a2730