[CCR] Tell user when multiple auto-follow patterns try to replicate the same data

[sebelga]

In order to fix a bug where the UI silently fail when 2 auto-follow patterns try to replicate the same index on the leader (see issue #27428) we need to fetch the CCR stats and display the possible errors for an auto-follow pattern.

This PR add 3 API endpoints for the stats

• GET /cross_cluster_replication/stats (all the stats coming from ES)
• GET /cross_cluster_replication/stats/auto-follow (only the auto-follow pattern stats)

Test

In order to reproduce the error:

• Create 2 auto-follow pattern with a similar leader index pattern (e.g. kiba* and kibana*
• Create an index on the remote cluster that matches both patterns. e.g:

PUT /kibana_sample

# body
{
  "settings": {
    "number_of_shards": 1,
    "soft_deletes.enabled": true
  }
}

Fixes #27428

[elasticmachine]

💔 Build Failed

• continuous-integration/kibana-ci/pull-request

[elasticmachine]

Pinging @elastic/es-ui

[sebelga]

retest

[elasticmachine]

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• continuous-integration/kibana-ci/pull-request

[sebelga]

@jen-huang I added the UI to fix the bug so you can test the complete flow. cheers!

[elasticmachine]

💔 Build Failed

• continuous-integration/kibana-ci/pull-request

[elasticmachine]

💚 Build Succeeded

• continuous-integration/kibana-ci/pull-request

[jen-huang]

Very nice, tested locally and code LGTM!

A timestamp field was added in ES for 6.7: elastic/elasticsearch#36947

We should conditionally show this information if it exists - but that can be done in a follow up PR since it's not needed for 6.6!

[sebelga]

Great thanks for the update on ES timestamp. We should ask them to ping us in the ticket issue when merging the PR for more visibility I think.