add configuration for http client keepalive timeout elastic

[cjenkscybercom]

Adds configuration for the keep-alive timeout for the underlying http client used for elastic

elasticsearch.http.keep_alive_timeout_ms

Default is 30000ms (30 seconds)

[cjenkscybercom]

Semi-related, I wonder if in the future we might leverage the spring-boot elasticsearch starter; it'd give us some configuration out of the box... https://docs.spring.io/spring-boot/docs/current/reference/html/application-properties.html#application-properties.data.spring.elasticsearch.connection-timeout https://docs.spring.io/spring-data/elasticsearch/docs/current/reference/html/

[shroffk]

At least in the past... this severely limited our ability to control the version of springboot + elastic we can deploy.

With elastic being shared between multiple services and many sites have different operations/maintenance schedules not having this flexibility would add quite a bit of pain.

However, this should be out end goal... a way to reduce the code we have to maintain.