Remove wpcom-migration customization from Login and Jetpack Connect

[jsnajdr]

This removes a no-longer-used customization of the /jetpack/connect/authorize and /log-in/jetpack pages when the user comes from a WP.com migration plugin flow (from=wpcom-migration query param. As you can read in #103445 (comment) the wpcom-migration plugin on WP.org has been changed to a completely different implementation and this flow is no longer used.

There were many design customizations as you can see in these /jetpack/connect/authorize screenshots:

Customized flow	Customization removed

The customized flow changed the vanilla Jetpack Connect screen by changing the colors (to WP.com blue), removing the Jetpack header, rendering a different header and subheader, different label on the "Approve" button, displaying the user name and gravatar differently... This is now all gone.

I'm keeping the customization that affect functionality: like redirecting to /start/site-migration or /start/account on certain conditions that involve the from=wpcom-migration query param. The flow will still work flawlessy if someone goes through it. But the visual customizations are all removed.

Testing instructions:

1. Go to /jetpack/connect/authorize in dev Calypso.
2. In client/jetpack-connect/controller.js, modify the line:

   const transformedQuery = parseAuthorizationQuery( query );
   

   into

   const transformedQuery = {};
   

   or

   const transformedQuery = { from: 'wpcom-migration' };
   

   so that you avoid the NoDirectAccessError screen.
3. Verify how the page is displayed pre- and post- this patch, both with wpcom-migration and without.

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-146137

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-146137&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-146137&env=a8c-for-agencies

[matticbot]

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

App Entrypoints (~203 bytes removed 📉 [gzipped])

name         parsed_size           gzip_size
entry-login       -613 B  (-0.0%)     -203 B  (-0.0%)

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

Sections (~440 bytes removed 📉 [gzipped])

name               parsed_size           gzip_size
jetpack-connect        -1279 B  (-0.1%)     -313 B  (-0.1%)
stepper-user-step       -210 B  (-0.0%)      -62 B  (-0.0%)
security                -210 B  (-0.0%)      -65 B  (-0.0%)
purchase-product         -46 B  (-0.0%)      -27 B  (-0.0%)

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

Async-loaded Components (~206 bytes removed 📉 [gzipped])

name                          parsed_size           gzip_size
async-load-design-blocks           -447 B  (-0.0%)     -148 B  (-0.0%)
async-load-signup-steps-user       -210 B  (-0.0%)      -58 B  (-0.0%)

React components that are loaded lazily, when a certain part of UI is displayed for the first time.

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.

[jsnajdr]

The this.retryingAuth condition is handled a few lines above. If we get to this statement, it's already guaranteed to be false.

[jsnajdr]

Here and at a few other places I'm reusing the existing redirectTo value. It's guaranteed to be non-empty because it satisfied checks for a substring.

[jsnajdr]

Here I'm moving the variable assignment closer to the (single) usage. Similarly for signupFlow a few lines below.

[jsnajdr]

Most of this condition is redundant since https://github.com/Automattic/wp-calypso/pull/83026/files#r1361480491 because if redirectTo is non-empty, the entire condition is true.

[matticbot]

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

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

• help-center
• notifications
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug remove/login-wpcom-migration-variant on your sandbox.