Scheduled Updates: Improve copy when there are no eligible plugins

[obenland]

Makes the message a bit easier to understand and includes a call to action.

Related to p1714576596695849-slack-C01A60HCGUA

Proposed Changes

• Updates string to make it a bit clearer.

Testing Instructions

• Checkout the branch and navigate to /plugins/scheduled-updates
• Select a WoA site that only contains managed plugins.

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-106245

Jetpack Cloud live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-106245&env=jetpack

Automattic for Agencies live (direct link)

https://calypso.live?image=registry.a8c.com/calypso/app:build-106245&env=a8c-for-agencies

[obenland]

Once approved, let's add the [Status] String Freeze label and wait for translations to complete before merging.

That way we don't introduce an untranslated string into an otherwise translated area of our product.

[matticbot]

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

Sections (~21 bytes added 📈 [gzipped])

name                             parsed_size           gzip_size
plugins                                +34 B  (+0.0%)      +21 B  (+0.0%)
jetpack-cloud-plugin-management        +34 B  (+0.0%)      +21 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.

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.

[zaerl]

More clear, good work.