Help Center: Show a spinner instead of "nothing found"

[alshakero]

Fixes: #97170

Proposed Changes

Screen.Recording.2024-12-06.at.17.20.53.mov

Why are these changes being made?

The UX was jarring.

Testing Instructions

1. Start a chat (with flag enabled = flags=help-center-experience).
2. Delete Calypso index DB in DevTools.
3. Refresh the page.
4. Open the Help Center.
5. In DevTools > Network, simulate Slow 3G.
6. Click "History"
7. A spinner should show.

[github-actions]

Calypso Live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-126798

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-126798&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-126798&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

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

To test WordPress.com changes, run install-plugin.sh $pluginSlug fix/show-loading-instead-nothing on your sandbox.

[matticbot]

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

Async-loaded Components (~24 bytes added 📈 [gzipped])

name                               parsed_size           gzip_size
async-load-automattic-help-center       +135 B  (+0.0%)      +24 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.

[agrullon95]

Working well. Simple, but great UX improvement!