[Request] Update all Use Case subsections

[Charelzard]

Description

Update all Use Cases sections: https://www.elastic.co/guide/en/security/current/assistant-use-cases.html

Use the following document to reference desired changes. https://docs.google.com/document/d/1qN5V-_Fq-NPgH1YaCRxNpYAdjGhoNtLXbfKu5kE_WN0/edit?usp=sharing

Background & resources

N/A

Which documentation set does this change impact?

ESS and serverless

ESS release

8.16

Serverless release

N/A

Feature differences

N/A

API docs impact

N/A

Prerequisites, privileges, feature flags

N/A

[Charelzard]

FYI @benironside @jamesspi