[Feature]: support index_template

[jgournet]

Requirement

As a jaeger admin, we're using Opensearch as the storage.
We have also migrated all our old "template" to "index_template" ( https://www.elastic.co/guide/en/elasticsearch/reference/current/index-templates.html ).

Problem

Problem is that when template AND index_template are mixed together, they do not behave well. One will take over and the other just does not work at all

Proposal

Move to index_template

Open questions

See discussion there on the bug, the error message and the resolution:
https://discuss.elastic.co/t/connecting-from-jaeger-tracing-to-elasticsearch/365713