#13226012 Site Migration: Show an error message when the site setup fails

Closes #90228

Proposed Changes

• Show an error message guiding the user to ask for support help
• Add tracking event when we don’t have success to finish the prepare the site.

Tech changes

Add configurations to manage the retry attempts and retry delay to optimize the test execution.

Testing Instructions

It is not possible to test using calypso.live because it requires code changes to force errors.

• Go to the line 6 on the file

  wp-calypso/client/landing/stepper/hooks/use-prepare-site-for-migration.ts

  Line 6
  in
  2a620b6

  const PLUGIN = { name: ‘migrate-guru/migrateguru’, slug: ‘migrate-guru’ };

• Replace the plugin const with const PLUGIN = { name: 'migrate-guru-wrong/migrateguru-wrong', slug: 'migrate-guru' };
• Run the migration flow and check if the last step shows a screen like this:

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the “[Status] String Freeze” label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
• For changes affecting Jetpack: Have we added the “[Status] Needs Privacy Updates” label if this pull request changes what data or activity we track or use (p4TIVU-aUh-p2)?