Domains: Remove unused domains/kracken-ui/max-characters-filter feature flag

[leonardost]

Proposed Changes

This PR removes the domains/kracken-ui/max-characters-filter feature flag which was always false and only present in development.json. The feature flag was introduced in #24718, where it was split from domains/kracken-ui/filters, and then it was disabled in #52874.

That flag gated a max length option when searching for domains. When provided, that option adds a max_characters parameter to the suggestion endpoint, which limits the length of the resulting domain name suggestions.

Why are these changes being made?

Removing obsolete and dead code.

Testing Instructions

Since this is only removing dead code, nothing should have changed, but please test:

• Code inspection
• Go to a domain search page (either in /start or searching for a domain for an existing site)
• Use the search filter and ensure it's working normally

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• https://wpcalypso.wordpress.com/devdocs/docs/testing/index.md 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-122400

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-122400&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-122400&env=a8c-for-agencies

[matticbot]

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

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

• notifications
• wpcom-block-editor

To test WordPress.com changes, run install-plugin.sh $pluginSlug update/remove-domains-kracken-ui-max-characters-filter-feature-flag on your sandbox.

[matticbot]

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

Sections (~348 bytes removed 📉 [gzipped])

name                  parsed_size           gzip_size
videopress-flow           -1448 B  (-0.1%)     -348 B  (-0.1%)
update-design-flow        -1448 B  (-0.1%)     -348 B  (-0.1%)
sensei-flow               -1448 B  (-0.2%)     -348 B  (-0.2%)
link-in-bio-tld-flow      -1448 B  (-0.1%)     -348 B  (-0.1%)
domains                   -1448 B  (-0.1%)     -348 B  (-0.1%)
copy-site-flow            -1448 B  (-0.2%)     -348 B  (-0.2%)

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 (~348 bytes removed 📉 [gzipped])

name                             parsed_size           gzip_size
async-load-signup-steps-domains      -1448 B  (-0.3%)     -348 B  (-0.2%)

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.

[leonardost]

This method only checked if maxCharacters is an integer, so it can be removed.

[leonardost]

Since getMaxCharactersValidationErrors only returned null, isValid was always true and this method always returned null, so it can be removed too.

[leonardost]

This only ever changed to true when hasValidationErrors returned true, which doesn't happen anymore. So this state property can be removed.