Protect Meets Core: Fix "0" rendered by conditional render chain

[nateweller]

Proposed changes:

• Casts .length values as strict booleans, to prevent the "0" value from being rendered.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

N/A

Does this pull request change what data or activity we track or use?

No

Testing instructions:

• On a site with a paid plan and no threat history, verify that no zero is rendered above the footer.

[github-actions]

Thank you for your PR!

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🔴 Action required: Please add missing changelog entries for the following projects: projects/plugins/protect

Use the Jetpack CLI tool to generate changelog entries by running the following command: jetpack changelog add.
Guidelines: /docs/writing-a-good-changelog-entry.md

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Protect plugin:

• Next scheduled release: none scheduled.

If you have any questions about the release process, please ask in the #jetpack-releases channel on Slack.