docs(llm-obs): combine Patterns setup docs for new Model/Runs on UI + scheduling

[aniszoubiramar]

Summary

• Combines the doc changes from docs(llm-obs): document scheduling for Patterns configs #37951 (Pattern run scheduling) and Update Patterns setup docs for new config UI #38524 (revamped Model / Runs on config UI) into a single, correctly-renumbered "Set up a Pattern" walkthrough.
• Uses "Runs on" (not "Runs") to match the just-shipped web-ui label rename (DataDog/web-ui#334514).

Supersedes #37951 and #38524 — those remain open pending doc-team review but their content now lives here combined and renumbered.

[github-actions]

Preview links (active after the build_preview check completes)

Modified Files

• https://docs-staging.datadoghq.com/anis.amar/llm-obs-patterns-docs-combined/llm_observability/monitoring/patterns

[janine-c]

Hey Anis, thank you for submitting this! I did a quick pass to apply some of our style guidelines and writing best practices. I went by what I could see in the UI (and added a link to make it easier for users to find), so if I changed anything concerning a future release, feel free to revert it. Let me know if you have any questions, and feel free to squash and merge whenever you're ready!

[aniszoubiramar]

Regarding commit bca3a0c we have a web-ui PR in progress https://github.com/DataDog/web-ui/pull/334514.