Decommission pages-builder

[apburnes]

With the completion of #4456, the pages-builder components needs to be decommissioned and deleted.

Acceptance criteria

• Delete the site-build-queue queue from the app, workers, and the bull board chore: Remove decommissioned site build queue related to pages-builder #4513
• Remove any documentation about the builder
• Delete the pages-builder- app
• Delete the builder CI pipeline
• Archive the pages-builder repo
• Update any diagrams reflecting the use of the builder chore: Updates pages build diagram to remove pages-builder cg-diagrams#148

[apburnes]

Schedule time to review the SSP and other documentation.

[apburnes]

SSP/diagras updated