SSR: Enable Login Section SSR for Mag-16 Locales

[yuliyan]

Related to #94712

Proposed Changes

• Enable SSR for the Login section for Mag-16 locales.

Why are these changes being made?

• We're looking to add localized meta description to the Login section. To achieve that, we need to enable SSR and load the locale data for Mag-16 locales.

Testing Instructions

• Code review.
• Visit /log-in/{mag-16-locale}, for example /log-in/de, and verify the SSR page source is localized.
• Visit /log-in and verify the page is served in English and verify previous behavior remains unchanged.
• Visit the Login section for non-mag-16 locale, for example /log-in/bg and verify the page is rendered on the client side and localized, i.e. works as it did before the changes.

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-119946

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-119946&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-119946&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 (~175637 bytes removed 📉 [gzipped])

name                   parsed_size            gzip_size
entry-login              +466186 B  (+29.9%)  +126325 B  (+27.3%)
entry-subscriptions        +1007 B   (+0.1%)    -2267 B   (-0.4%)
entry-main                  +905 B   (+0.0%)     -991 B   (-0.2%)
entry-stepper               -873 B   (-0.0%)    -1029 B   (-0.2%)
entry-domains-landing       -671 B   (-0.1%)     -524 B   (-0.3%)
entry-browsehappy           -445 B   (-0.2%)     -122 B   (-0.2%)

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

Async-loaded Components (~53216 bytes removed 📉 [gzipped])

name                                                                              parsed_size             gzip_size
async-load-calypso-layout-masterbar-checkout-tsx                                    -114691 B  (deleted)   -39903 B  (deleted)
async-load-calypso-blocks-support-article-dialog-dialog                             -101846 B   (-54.0%)   -30933 B   (-52.4%)
async-load-automattic-help-center                                                    +17348 B    (+3.1%)    +4771 B    (+2.9%)
async-load-calypso-lib-store-sandbox-helper                                          -16262 B   (-32.0%)    -4432 B   (-30.0%)
async-load-purchase-modal-wrapper                                                     +6836 B    (+1.9%)    +2157 B    (+1.9%)
async-load-my-sites-checkout-purchase-modal-is-eligible-for-one-click-checkou...      +6836 B    (+1.9%)    +2147 B    (+2.0%)
async-load-calypso-state-lib-automated-transfer-middleware                            -6343 B   (-23.7%)    -2221 B   (-26.8%)
async-load-calypso-lib-account-settings-helper                                        -5431 B    (-3.4%)    -1544 B    (-3.2%)
async-load-calypso-lib-preferences-helper                                             -4153 B   (-48.7%)    -1370 B   (-51.3%)
async-load-calypso-layout-command-palette                                             +3972 B    (+1.9%)    +1473 B    (+2.6%)
async-load-masterbar-launchpad-navigator                                              +3776 B    (+6.7%)     +975 B    (+5.5%)
async-load-calypso-blocks-jitm-templates-home-task                                    +3776 B    (+9.4%)     +977 B    (+6.7%)
async-load-automattic-whats-new                                                       +3776 B   (+16.8%)     +967 B   (+12.1%)
async-load-calypso-lib-react-query-devtools-helper                                    -1528 B  (deleted)     -684 B  (deleted)
async-load-calypso-components-sites-popover                                           +1008 B    (+0.8%)     +425 B    (+1.1%)
async-load-calypso-blocks-support-article-dialog                                      -1008 B   (-35.4%)     -269 B   (-24.3%)
async-load-calypso-layout-masterbar-drafts-popover                                     +567 B    (+2.0%)     +272 B    (+3.0%)
async-load-calypso-notifications                                                       +513 B    (+0.3%)     +131 B    (+0.2%)
async-load-calypso-lib-network-connection                                              -369 B    (-8.1%)     -146 B    (-8.4%)
async-load-calypso-components-jetpack-portal-nav                                       +248 B    (+0.5%)      +68 B    (+0.5%)
async-load-calypso-layout-masterbar-checkout                                           -196 B    (-0.3%)     -547 B    (-2.2%)

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.

[matticbot]

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

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

• blaze-dashboard
• command-palette-wp-admin
• help-center
• notifications
• odyssey-stats
• whats-new
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug add/localized-login-ssr on your sandbox.