VideoPress upgrade redirect link is broken

### Impacted plugin

Jetpack

### Quick summary

After inserting a VideoPress block while in the site editor on a site with a dotcom personal plan, I choice to upgrade my plan. After upgrading it tried to send me back to `https://wordpress.com/edit/wp_template/.wordpress.com/pub/feelingood//index?plan_upgraded=1`

I've never seen a Wordpress.com/edit url before, and while it doesn't 404, it doesn't seem to do much else either.

### Steps to reproduce

1. Get a wp.com site on a free/personal plan
2. Open the site editor
3. Edit the template by inserting a VideoPress block
4. Follow the dialog to upgrade your plan
5. Go through checkout

### A clear and concise description of what you expected to happen.

To be returned back to the site editor, to continue to upload a video and use VideoPress. The URL would be something like:

https://.wordpress.com/wp-admin/site-editor.php?postId=pub%2Ffeelingood%2F%2Findex&postType=wp_template&canvas=edit&plan_upgraded=1

### What actually happened

Was sent to `https://wordpress.com/edit/wp_template/.wordpress.com/pub/feelingood//index?plan_upgraded=1` which displays a white screen of death.

### Impact

One

### Available workarounds?

Yes, easy to implement

### Platform (Simple and/or Atomic)

_No response_

### Logs or notes

_No response_

No source file or test is named. Reproduce the VideoPress upgrade flow from the site editor and compare the resulting redirect with the expected wp-admin/site-editor.php URL; done means returning to the site editor without a white screen.

Written by the indexing model from the issue text.