Bring back APM Server Standalone

[graphaelli]

Kibana version: 8.12.1

Following the effort to bring APM Server standalone back to good standing in https://github.com/elastic/apm-dev/issues/917, the instructions in kibana for migrating to fleet managed need an update to reflect that standalone is not deprecated but migrating to fleet managed on ESS is still a reasonable thing to do.

As a first step, let's remove the legacy terminology in

kibana/x-pack/plugins/apm/public/components/app/settings/schema/schema_overview.tsx

Line 119 in e2aefd1

'You are currently using APM Server binary. This legacy option is deprecated since version 7.16 and is being replaced by a managed APM Server in Elastic Agent from version 8.0.',

.

Perhaps:

'You are currently using APM Server binary. You may choose to migrated to managed APM Server in Elastic Agent.',

@akhileshpok would a higher level consideration of this flow fit into your efforts on onboarding (or otherwise?)

[elasticmachine]

Pinging @elastic/apm-ui (Team:APM)