[Serverless] Disable Search Sessions

[ElenaStoeva]

Partially addresses #157756

Summary

This PR disables the Search Sessions plugin for serverless.

How to test:

1. Start Elasticsearch with yarn es snapshot and Kibana with yarn serverless-{mode} where {mode} can be es, security, or oblt.
2. Verify that the Search Sessions app is not accessible and its path (app/management/kibana/search_sessions) leads to the Stack Management landing page.

[kibana-ci]

💚 Build Succeeded

• Buildkite Build
• Commit: 0dadb70

Metrics [docs]

Unknown metric groups

ESLint disabled line counts

id	before	after	diff
enterpriseSearch	19	21	+2
securitySolution	399	403	+4
total			+6

Total ESLint disabled count

id	before	after	diff
enterpriseSearch	20	22	+2
securitySolution	479	483	+4
total			+6

To update your PR or re-run it, just comment with:
@elasticmachine merge upstream

cc @ElenaStoeva

[elasticmachine]

Pinging @elastic/platform-deployment-management (Team:Deployment Management)

[kertal]

@davismcphee one thing to check, I think we're using searchSessions in the unified histogram layout:

kibana/src/plugins/discover/public/application/main/components/layout/discover_histogram_layout.tsx

Line 36 in 8f41ab0

const searchSessionId = useObservable(stateContainer.searchSessionManager.searchSessionId$);

so the question if this still works, but anyway, it might be better to search for an alternative since I don't think we need the searchSessionManager service anywhere else in the code

[davismcphee]

@davismcphee one thing to check, I think we're using searchSessions in the unified histogram layout:

kibana/src/plugins/discover/public/application/main/components/layout/discover_histogram_layout.tsx

Line 36 in 8f41ab0

const searchSessionId = useObservable(stateContainer.searchSessionManager.searchSessionId$);

so the question if this still works, but anyway, it might be better to search for an alternative since I don't think we need the searchSessionManager service anywhere else in the code

@kertal The main thing we're using it for here is to determine if the first search has run yet when navigating to Discover. If we can find another way to check for this, I think we can likely remove searchSessionId from this check:

kibana/src/plugins/discover/public/application/main/components/layout/discover_histogram_layout.tsx

Lines 47 to 49 in 8f41ab0

	if (!searchSessionId && !isPlainRecord) {
	return null;
	}

Otherwise we may have to check if the search session plugin is enabled and add that to the check as well.

Although in either case we'll still need to be able to retrieve the searchSessionId (if one exists) to pass down to Unified Histogram.

[davismcphee]

Pulled and tested locally, and I was unable to access app/management/kibana/search_sessions as expected. I also did some testing in Discover and everything seems to working fine there as well. LGTM 👍

@kertal It looks like this change just disables the use of search sessions in searches, but the search session service is still available, and it still returns IDs so it doesn't seem to have any impact on Discover from what I can tell.

[kertal]

Thx for checking!

[ElenaStoeva]

Thanks a lot for the review @davismcphee and @kertal!