Congrats pages: rewrite approach for setting up Titan mailbox

[nightnei]

Related to https://github.com/Automattic/wp-calypso/issues/87334

Proposed Changes

Currently, after setting up the mailbox, users will be taken to the Congrats Page within the dashboard experience, which is incorrect. Since the Congrats Page is meant to be shown in the checkout experience (without the sidebar and without the admin bar). With this PR we are redirecting user to the page with the list of mailboxes and show success notice.

Testing Instructions

1. You need a domain with Titan subcription
2. Open in via Upgrades -> Emails -> Select if from the list
3. Remove mailboxes
4. You should see Setup mailbox button, click on it
5. Fill in fields and proceed
6. Assert that you are redirected to the previous page and see success notice (Previous approach - we were landed to congrats page)

[github-actions[bot]]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-99428

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-99428&env=jetpack

[matticbot]

Here is how your PR affects size of JS and CSS bundles shipped to the user's browser:

App Entrypoints (~7 bytes added 📈 [gzipped])

name                   parsed_size           gzip_size
entry-stepper               -151 B  (-0.0%)      +34 B  (+0.0%)
entry-main                  -151 B  (-0.0%)      +34 B  (+0.0%)
entry-domains-landing        -79 B  (-0.0%)       -9 B  (-0.0%)

Common code that is always downloaded and parsed every time the app is loaded, no matter which route is used.

Sections (~1202 bytes removed 📉 [gzipped])

name                             parsed_size           gzip_size
email                               -15281 B  (-2.3%)    -5480 B  (-2.8%)
checkout                              -964 B  (-0.1%)     -838 B  (-0.2%)
themes                                -737 B  (-0.1%)      -26 B  (-0.0%)
jetpack-cloud-plugin-management       -325 B  (-0.0%)      +83 B  (+0.0%)
plugins                               -312 B  (-0.0%)      -58 B  (-0.0%)
marketplace                           -208 B  (-0.0%)      -69 B  (-0.0%)
plans                                 +196 B  (+0.0%)    +1570 B  (+0.4%)
theme                                 -142 B  (-0.0%)      -53 B  (-0.0%)
settings                               +51 B  (+0.0%)     -129 B  (-0.1%)

Sections contain code specific for a given set of routes. Is downloaded and parsed only when a particular route is navigated to.

Legend

What is parsed and gzip size?

Parsed Size: Uncompressed size of the JS and CSS files. This much code needs to be parsed and stored in memory. Gzip Size: Compressed size of the JS and CSS files. This much data needs to be downloaded over network.

Generated by performance advisor bot at iscalypsofastyet.com.

[a8ci18n]

This Pull Request is now available for translation here: https://translate.wordpress.com/deliverables/11358411

Some locales (Hebrew, Japanese) have been temporarily machine-translated due to translator availability. All other translations are usually ready within a few days. Untranslated and machine-translated strings will be sent for translation next Monday and are expected to be completed by the following Friday.

Thank you @nightnei for including a screenshot in the description! This is really helpful for our translators.

[a8ci18n]

Translation for this Pull Request has now been finished.

[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 nightnei/rewtriteApproachForSetupMailboxCongratsPage on your sandbox.