[Cases Plugin] Migrate authc.getCurrentUser usage to coreStart.security

[tsullivan]

Part of #186574

Summary

This PR migrates the method to access a Cases Plugin view model field, which consumes authc.getCurrentUser, to use coreStart.security.

Background: This PR serves as an example of a plugin migrating away from depending on the Security plugin, which is a high priority effort for the last release before 9.0.

Checklist

Delete any items that are not applicable to this PR.

• Unit or functional tests were updated or added to match the most common scenarios

[tsullivan]

Removed the else as it would have been dead code. The new security service comes from Core and is always available.

[tsullivan]

Note, KibanaContextProvider isn't well typed for custom service objects like this. See the FIXME in x-pack/plugins/cases/public/common/lib/kibana/kibana_react.ts

[tsullivan]

/ci

[kibana-ci]

💔 Build Failed

• Buildkite Build
• Commit: 553e58c
• Interpreting CI Failures

Failed CI Steps

• Check Types
• Cases Cypress Tests on Security Solution
• Cases Cypress Tests on Security Solution

Test Failures

• [job] [logs] Cases Cypress Tests on Security Solution / Cases Creates a new case with timeline and opens the timeline Creates a new case with timeline and opens the timeline
• [job] [logs] Cases Cypress Tests on Security Solution / Cases Creates a new case with timeline and opens the timeline Creates a new case with timeline and opens the timeline

Metrics [docs]

Async chunks

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

id	before	after	diff
cases	479.4KB	479.4KB	+27.0B

Page load bundle

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

id	before	after	diff
cases	151.6KB	151.4KB	-239.0B

Unknown metric groups

References to deprecated APIs

id	before	after	diff
cases	33	32	-1

History

• 💔 Build #218571 failed db2cc2e

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

[tsullivan]

Getting a TypeError in a functional test, due to const { securityService } = useKibana().services;

It's extremely difficult to track down which provider hasn't passed in the correct service. I'll close this now, as these changes can come later.