Update import-hosted-site reference from /start/hosting to new flow

[andres-blanco]

Closes #90648

Proposed Changes

While this shouldn't be merged because of missing pieces in the flow (mainly #90710) I was exploring some code and made this changes to test.

Why are these changes being made?

To point /start/hosting to a Migrate Guru flow

Testing Instructions

• Apply this patch or follow the calypso.live link
• Go to /start/hosting
• Select Migrate Site
• Verify you get redirected to /setup/hosted-site-migration/site-migration-identify

Tracking

To track the performance of this link, the calypso_signup_actions_submit_step track event with these props:

• step: hosting-decider
• stepper_hosting_flow: hosted-site-migration

can be used as a starting point for the funnels.

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)?

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-108265

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-108265&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-108265&env=a8c-for-agencies

[matticbot]

This PR does not affect the size of JS and CSS bundles shipped to the user's browser.

Generated by performance advisor bot at iscalypsofastyet.com.

[matticbot]

This PR modifies the release build for the following Calypso Apps:

For info about this notification, see here: PCYsg-OT6-p2

• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug add/move-to-migrate-guru-start-hosting on your sandbox.

[sixhours]

This is working for me!