logs about updating IndexSetting should be more detailed

[kkewwei]

ES_VERSION: 7.3.1
Description of the problem including expected versus actual behavior:
When updating index setting like this:
PUT index1/_settings { "index": { "merge": { "policy": { "max_merge_at_once": "5" } } } }
and relevent log is:
[2019-12-03T21:59:14,065][INFO ][o.e.c.s.IndexScopedSettings] [node-1] updating [index.merge.policy.max_merge_at_once] from [10] to [5]
according to the log, I don't know which index is updated, If we could add the index name in the log.

[elasticmachine]

Pinging @elastic/es-core-infra (:Core/Infra/Settings)

[DaveCTurner]

Seems like a reasonable thing to want @kkewwei. Would you care to work on a PR?

[kkewwei]

It's my pleasure to do it.

[rachana-prajapati]

Is this item still open?

[kkewwei]

@rachana-prajapati, yes, you can see it it the pr.