…#195818)

## Summary

The Security Solution Entity Store feature will now be available by
default. However, there will be a flag that can be switched on, if
desired, to **disable** that feature entirely.

Regardless of whether this flag is enabled or not, Security's Entity
Store is still only fully enabled through an enablement workflow. In
other words, a Security Solution customer must turn on the feature
through an onboarding workflow in order to enable its features.

Additionally, we are disabling this feature in Serverless at first, to
perform proper Serverless load/performance testing. (We do not expect it
to be significantly different than ESS/ECH, but are doing so out of an
abundance of caution).

---------

Co-authored-by: Pablo Machado <pablo.nevesmachado@elastic.co>
(cherry picked from commit ea582dc)

# Conflicts:
#	config/serverless.security.yml
#	x-pack/test/security_solution_api_integration/test_suites/entity_analytics/entity_store/trial_license_complete_tier/engine.ts