[APM] Support sampling ttl configuration in apm integration policy

[carsonip]

Describe the feature:

apm integration policy configuration UI should support configuring tail sampling ttl. Should be in 9.1 and backported to 8.19.

The copy should follow elastic/docs-content#1269

Part of elastic/apm-server#13525

Describe a specific use case for the feature:

[elasticmachine]

Pinging @elastic/obs-ux-infra_services-team (Team:obs-ux-infra_services)

[carsonip]

@smith not sure if apm:Agent Configuration is the right label, if the label is more about agent "central" configuration feature. This ttl configuration is in the apm integration package. Possibly apm:fleet?

[cauemarcondes]

Moving it back to refining as we still need to decide some copies and wait for @carsonip 's PR to be merged.