Adds fluentd-elasticsearch

Part of gitlab-com/gl-infra/delivery#1961 (closed)

This is a migration of fluentd-elasticsearch helm chart and deployment from

https://gitlab.com/gitlab-com/gl-infra/k8s-workloads/gitlab-helmfiles/-/tree/master/releases/fluentd

and

https://dev.gitlab.org/gitlab/charts/fluentd-elasticsearch

This currently is only deploying into the pre environment, for testing.