[Discover] Remove Serverless plugin dependency

[davismcphee]

Summary

This PR removes the serverless plugin dependency from Discover and replaces it with a showInlineTopNav method on the Discover plugin contract, which gets called from within serverless project plugins to enable the serverless top nav. It also modifies the DiscoverCustomizationContext and moves it to the customizations folder, as well as consolidating customization context mocks, to help lay some groundwork for upcoming Discover extensions work.

Checklist

• Any text added follows EUI's writing guidelines, uses sentence case text and includes i18n support
• Documentation was added for features that require explanation or tutorials
• Unit or functional tests were updated or added to match the most common scenarios
• Flaky Test Runner was used on any tests changed
• Any UI touched in this PR is usable by keyboard only (learn more about keyboard accessibility)
• Any UI touched in this PR does not create any new axe failures (run axe in browser: FF, Chrome)
• If a plugin configuration key changed, check if it needs to be allowlisted in the cloud and added to the docker list
• This renders correctly on smaller devices using a responsive layout. (You can test this in your browser)
• This was checked for cross-browser compatibility

For maintainers

• This was checked for breaking API changes and was labeled appropriately

[davismcphee]

/ci

[davismcphee]

/ci

[kibana-ci]

💛 Build succeeded, but was flaky

• Buildkite Build
• Commit: abe89db
• Storybooks Preview

Failed CI Steps

• Jest Integration Tests #7
• Defend Workflows Cypress Tests on Serverless #10

Test Failures

• [job] [logs] Defend Workflows Cypress Tests on Serverless #10 / User Roles for Security Complete PLI with Endpoint Complete addon for role: endpoint_operations_analyst should have access to response action: suspend-process should have access to response action: suspend-process

Metrics [docs]

Public APIs missing comments

Total count of every public API that lacks a comment. Target amount is 0. Run node scripts/build_api_docs --plugin [yourplugin] --stats comments for more detailed information.

id	before	after	diff
discover	109	110	+1

Async chunks

Total size of all lazy-loaded chunks that will be downloaded as the user navigates the app

id	before	after	diff
discover	581.3KB	581.5KB	+147.0B

Page load bundle

Size of the bundles that are downloaded on every page load. Target size is below 100kb

id	before	after	diff
discover	33.2KB	33.3KB	+59.0B
observabilityLogsExplorer	15.3KB	15.2KB	-52.0B
securitySolutionServerless	35.9KB	36.0KB	+30.0B
serverlessObservability	26.6KB	26.6KB	+55.0B
serverlessSearch	19.3KB	19.3KB	+30.0B
total			+122.0B

Unknown metric groups

API count

id	before	after	diff
discover	157	158	+1

History

• 💔 Build #196301 failed beaa2b7

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

cc @davismcphee

[tonyghiani]

logs_explorer changes LGTM 👌

[jughosta]

LGTM 👍

[semd]

Security Solution changes LGTM

[andreadelrio]

Design changes LGTM.